wdiff rfc8621v3.txt rfc8621.txt

Internet Engineering Task Force (IETF) N. Jenkins
Request for Comments: 8621 Fastmail
Updates: 5788 C. Newman
Category: Standards Track Oracle
ISSN: 2070-1721 June August 2019

The JSON Meta Application Protocol (JMAP) for Mail

Abstract

This document specifies a data model for synchronising email data
with a server using the JSON Meta Application Protocol (JMAP).
Clients can use this to efficiently search, access, organise, and
send messages, and to get push notifications for fast
resynchronisation when new messages are delivered or a change is made
in another client.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8621.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Additions to the Capabilities Object . . . . . . . . . . 5
1.3.1. urn:ietf:params:jmap:mail . . . . . . . . . . . . . . 5
1.3.2. urn:ietf:params:jmap:submission . . . . . . . . . . . 7
1.3.3. urn:ietf:params:jmap:vacationresponse . . . . . . . . 8
1.4. Data Type Support in Different Accounts . . . . . . . . . 8
1.5. Push . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.5.1. Example . . . . . . . . . . . . . . . . . . . . . . . 9
1.6. Ids . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2. Mailboxes . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1. Mailbox/get . . . . . . . . . . . . . . . . . . . . . . . 13
2.2. Mailbox/changes . . . . . . . . . . . . . . . . . . . . . 14
2.3. Mailbox/query . . . . . . . . . . . . . . . . . . . . . . 14
2.4. Mailbox/queryChanges . . . . . . . . . . . . . . . . . . 15
2.5. Mailbox/set . . . . . . . . . . . . . . . . . . . . . . . 15
2.6. Example . . . . . . . . . . . . . . . . . . . . . . . . . 16
3. Threads . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.1. Thread/get . . . . . . . . . . . . . . . . . . . . . . . 21
3.1.1. Example . . . . . . . . . . . . . . . . . . . . . . . 21
3.2. Thread/changes . . . . . . . . . . . . . . . . . . . . . 21
4. Emails . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1. Properties of the Email Object . . . . . . . . . . . . . 22
4.1.1. Metadata . . . . . . . . . . . . . . . . . . . . . . 23
4.1.2. Header Fields Parsed Forms . . . . . . . . . . . . . 25
4.1.3. Header Fields Properties . . . . . . . . . . . . . . 31
4.1.4. Body Parts . . . . . . . . . . . . . . . . . . . . . 33
4.2. Email/get . . . . . . . . . . . . . . . . . . . . . . . . 40
4.2.1. Example . . . . . . . . . . . . . . . . . . . . . . . 42
4.3. Email/changes . . . . . . . . . . . . . . . . . . . . . . 43
4.4. Email/query . . . . . . . . . . . . . . . . . . . . . . . 44
4.4.1. Filtering . . . . . . . . . . . . . . . . . . . . . . 44
4.4.2. Sorting . . . . . . . . . . . . . . . . . . . . . . . 47
4.4.3. Thread Collapsing . . . . . . . . . . . . . . . . . . 48
4.5. Email/queryChanges . . . . . . . . . . . . . . . . . . . 49
4.6. Email/set . . . . . . . . . . . . . . . . . . . . . . . . 49
4.7. Email/copy . . . . . . . . . . . . . . . . . . . . . . . 51
4.8. Email/import . . . . . . . . . . . . . . . . . . . . . . 52
4.9. Email/parse . . . . . . . . . . . . . . . . . . . . . . . 54
4.10. Examples . . . . . . . . . . . . . . . . . . . . . . . . 56
5. Search Snippets . . . . . . . . . . . . . . . . . . . . . . . 66
5.1. SearchSnippet/get . . . . . . . . . . . . . . . . . . . . 67
5.2. Example . . . . . . . . . . . . . . . . . . . . . . . . . 68
6. Identities . . . . . . . . . . . . . . . . . . . . . . . . . 69
6.1. Identity/get . . . . . . . . . . . . . . . . . . . . . . 70
6.2. Identity/changes . . . . . . . . . . . . . . . . . . . . 70
6.3. Identity/set . . . . . . . . . . . . . . . . . . . . . . 71
6.4. Example . . . . . . . . . . . . . . . . . . . . . . . . . 71
7. Email Submission . . . . . . . . . . . . . . . . . . . . . . 72
7.1. EmailSubmission/get . . . . . . . . . . . . . . . . . . . 78
7.2. EmailSubmission/changes . . . . . . . . . . . . . . . . . 78
7.3. EmailSubmission/query . . . . . . . . . . . . . . . . . . 78
7.4. EmailSubmission/queryChanges . . . . . . . . . . . . . . 79
7.5. EmailSubmission/set . . . . . . . . . . . . . . . . . . . 79
7.5.1. Example . . . . . . . . . . . . . . . . . . . . . . . 81
8. Vacation Response . . . . . . . . . . . . . . . . . . . . . . 84
8.1. VacationResponse/get . . . . . . . . . . . . . . . . . . 85
8.2. VacationResponse/set . . . . . . . . . . . . . . . . . . 85
9. Security Considerations . . . . . . . . . . . . . . . . . . . 85
9.1. EmailBodyPart Value . . . . . . . . . . . . . . . . . . . 85
9.2. HTML Email Display . . . . . . . . . . . . . . . . . . . 86
9.3. Multiple Part Display . . . . . . . . . . . . . . . . . . 88
9.4. Email Submission . . . . . . . . . . . . . . . . . . . . 88
9.5. Partial Account Access . . . . . . . . . . . . . . . . . 89
9.6. Permission to Send from an Address . . . . . . . . . . . 89
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 90
10.1. JMAP Capability Registration for "mail" . . . . . . . . 90
10.2. JMAP Capability Registration for "submission" . . . . . 90
10.3. JMAP Capability Registration for "vacationresponse" . . 91
10.4. IMAP and JMAP Keywords Registry . . . . . . . . . . . . 91
10.4.1. Registration of JMAP Keyword "$draft" . . . . . . . 92
10.4.2. Registration of JMAP Keyword "$seen" . . . . . . . . 93
10.4.3. Registration of JMAP Keyword "$flagged" . . . . . . 93 94
10.4.4. Registration of JMAP Keyword "$answered" . . . . . . 94
10.4.5. Registration of "$recent" Keyword . . . . . . . . . 95
10.5. IMAP Mailbox Name Attributes Registry . . . . . . . . . 96
10.5.1. Registration of "inbox" Role . . . . . . . . . . . . 96
10.6. JMAP Error Codes Registry . . . . . . . . . . . . . . . 96
10.6.1. mailboxHasChild . . . . . . . . . . . . . . . . . . 96
10.6.2. mailboxHasEmail . . . . . . . . . . . . . . . . . . 96
10.6.3. blobNotFound . . . . . . . . . . . . . . . . . . . . 97
10.6.4. tooManyKeywords . . . . . . . . . . . . . . . . . . 97
10.6.5. tooManyMailboxes . . . . . . . . . . . . . . . . . . 97
10.6.6. invalidEmail . . . . . . . . . . . . . . . . . . . . 97 98
10.6.7. tooManyRecipients . . . . . . . . . . . . . . . . . 98
10.6.8. noRecipients . . . . . . . . . . . . . . . . . . . . 98
10.6.9. invalidRecipients . . . . . . . . . . . . . . . . . 98
10.6.10. forbiddenMailFrom . . . . . . . . . . . . . . . . . 98 99
10.6.11. forbiddenFrom . . . . . . . . . . . . . . . . . . . 99
10.6.12. forbiddenToSend . . . . . . . . . . . . . . . . . . 99
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 99
11.1. Normative References . . . . . . . . . . . . . . . . . . 99 100
11.2. Informative References . . . . . . . . . . . . . . . . . 103
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 104

1. Introduction

The JSON Meta Application Protocol (JMAP) [RFC8620] is a generic
protocol for synchronising data, such as mail, calendars, or contacts
between a client and a server. It is optimised for mobile and web
environments and aims to provide a consistent interface to different
data types.

This specification defines a data model for accessing a mail store
over JMAP, allowing you to query, read, organise, and submit mail for
sending.

The data model is designed to allow a server to provide consistent
access to the same data via IMAP [RFC3501] as well as JMAP. As in
IMAP, a message must belong to a mailbox; however, in JMAP, its id
does not change if you move it between mailboxes, and the server may
allow it to belong to multiple mailboxes simultaneously (often
exposed in a user agent as labels rather than folders).

As in IMAP, messages may also be assigned zero or more keywords:
short arbitrary strings. These are primarily intended to store
metadata to inform client display, such as unread status or whether a
message has been replied to. An IANA registry allows common
semantics to be shared between clients and extended easily in the
future.

A message and its replies are linked on the server by a common Thread
id. Clients may fetch the list of messages with a particular Thread
id to more easily present a threaded or conversational interface.

Permissions for message access happen on a per-mailbox basis.
Servers may give the user restricted permissions for certain
mailboxes, for example, if another user's inbox has been shared as
read-only with them.

1.1. Notational Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.

Type signatures, examples, and property descriptions in this document
follow the conventions established in Section 1.1 of [RFC8620]. Data
types defined in the core specification are also used in this
document.

Servers MUST support all properties specified for the new data types
defined in this document.

1.2. Terminology

This document uses the same terminology as in the core JMAP
specification.

The terms Mailbox, Thread, Email, SearchSnippet, EmailSubmission and
VacationResponse (with that specific capitalisation) are used to
refer to the data types defined in this document and instances of
those data types.

The term message refers to a document in Internet Message Format, as
described in [RFC5322]. The Email data type represents messages in
the mail store and associated metadata.

1.3. Additions to the Capabilities Object

The capabilities object is returned as part of the JMAP Session
object; see [RFC8620], Section 2.

This document defines three additional capability URIs.

1.3.1. urn:ietf:params:jmap:mail

This represents support for the Mailbox, Thread, Email, and
SearchSnippet data types and associated API methods. The value of
this property in the JMAP session "capabilities" property is an empty
object.

The value of this property in an account's "accountCapabilities"
property is an object that MUST contain the following information on
server capabilities and permissions for that account:

o maxMailboxesPerEmail: "UnsignedInt|null"

The maximum number of Mailboxes (see Section 2) that can be can
assigned to a single Email object (see Section 4). This MUST be
an integer >= 1, or null for no limit (or rather, the limit is
always the number of Mailboxes in the account).

o maxMailboxDepth: "UnsignedInt|null"
The maximum depth of the Mailbox hierarchy (i.e., one more than
the maximum number of ancestors a Mailbox may have), or null for
no limit.

o maxSizeMailboxName: "UnsignedInt"

The maximum length, in (UTF-8) octets, allowed for the name of a
Mailbox. This MUST be at least 100, although it is recommended
servers allow more.

o maxSizeAttachmentsPerEmail: "UnsignedInt"

The maximum total size of attachments, in octets, allowed for a
single Email object. A server MAY still reject the import or
creation of an Email with a lower attachment size total (for
example, if the body includes several megabytes of text, causing
the size of the encoded MIME structure to be over some server-
defined limit).

Note that this limit is for the sum of unencoded attachment sizes.
Users are generally not knowledgeable about encoding overhead,
etc., nor should they need to be, so marketing and help materials
normally tell them the "max size attachments". This is the
unencoded size they see on their hard drive, so this capability
matches that and allows the client to consistently enforce what
the user understands as the limit.

The server may separately have a limit for the total size of the
message [RFC5322], created by combining the attachments (often
base64 encoded) with the message headers and bodies. For example,
suppose the server advertises "maxSizeAttachmentsPerEmail:
50000000" (50 MB). The enforced server limit may be for a message
size of 70000000 octets. Even with base64 encoding and a 2 MB
HTML body, 50 MB attachments would fit under this limit.

o emailQuerySortOptions: "String[]"

A list of all the values the server supports for the "property"
field of the Comparator object in an "Email/query" sort (see
Section 4.4.2). This MAY include properties the client does not
recognise (for example, custom properties specified in a vendor
extension). Clients MUST ignore any unknown properties in the
list.

o mayCreateTopLevelMailbox: "Boolean"

If true, the user may create a Mailbox (see Section 2) in this
account with a null parentId. (Permission for creating a child of
an existing Mailbox is given by the "myRights" property on that
Mailbox.)

1.3.2. urn:ietf:params:jmap:submission

This represents support for the Identity and EmailSubmission data
types and associated API methods. The value of this property in the
JMAP session "capabilities" property is an empty object.

The value of this property in an account's "accountCapabilities"
property is an object that MUST contain the following information on
server capabilities and permissions for that account:

o maxDelayedSend: "UnsignedInt"

The number in seconds of the maximum delay the server supports in
sending (see the EmailSubmission object description). This is 0
if the server does not support delayed send.

o submissionExtensions: "String[String[]]"

The set of SMTP submission extensions supported by the server,
which the client may use when creating an EmailSubmission object
(see Section 7). Each key in the object is the "ehlo-name", and
the value is a list of "ehlo-args".

A JMAP implementation that talks to a submission server [RFC6409]
SHOULD have a configuration setting that allows an administrator
to modify the set of submission EHLO capabilities it may expose on
this property. This allows a JMAP server to easily add access to
a new submission extension without code changes. By default, the
JMAP server should hide EHLO capabilities that have to do with the
transport mechanism and thus are only relevant to the JMAP server
(for example, PIPELINING, CHUNKING, or STARTTLS).

Examples of Submission extensions to include:

* FUTURERELEASE [RFC4865]

* SIZE [RFC1870]

* DSN [RFC3461]

* DELIVERYBY [RFC2852]

* MT-PRIORITY [RFC6710]
A JMAP server MAY advertise an extension and implement the
semantics of that extension locally on the JMAP server even if a
submission server used by JMAP doesn't implement it.

The full IANA registry of submission extensions can be found at
<https://www.iana.org/assignments/mail-parameters>.

1.3.3. urn:ietf:params:jmap:vacationresponse

This represents support for the VacationResponse data type and
associated API methods. The value of this property is an empty
object in both the JMAP session "capabilities" property and an
account's "accountCapabilities" property.

1.4. Data Type Support in Different Accounts

The server MUST include the appropriate capability strings as keys in
the "accountCapabilities" property of any account with which the user
may use the data types represented by that URI. Supported data types
may differ between accounts the user has access to. For example, in
the user's personal account, they may have access to all three sets
of data, but in a shared account, they may only have data for
"urn:ietf:params:jmap:mail". This means they can access
Mailbox/Thread/Email data in the shared account but are not allowed
to send as that account (and so do not have access to Identity/
EmailSubmission objects) or view/set its VacationResponse.

1.5. Push

Servers MUST support the JMAP push mechanisms, as specified in
[RFC8620], Section 7, to receive notifications when the state changes
for any of the types defined in this specification.

In addition, servers that implement the "urn:ietf:params:jmap:mail"
capability MUST support pushing state changes for a type called
"EmailDelivery". There are no methods to act on this type; it only
exists as part of the push mechanism. The state string for this MUST
change whenever a new Email is added to the store, but it SHOULD NOT
change upon any other change to the Email objects, for example, if
one is marked as read or deleted.

Clients in battery-constrained environments may wish to delay
fetching changes initiated by the user but fetch new Emails
immediately so they can notify the user. To do this, they can
register for pushes for the EmailDelivery type rather than the Email
type (as defined in Section 4).

1.5.1. Example

The client has registered for push notifications (see [RFC8620]) just
for the EmailDelivery type. The user marks an Email as read on
another device, causing the state string for the Email type to
change; however, as nothing new was added to the store, the
EmailDelivery state does not change and nothing is pushed to the
client. A new message arrives in the user's inbox, again causing the
Email state to change. This time, the EmailDelivery state also
changes, and a StateChange object is pushed to the client with the
new state string. The client may then resync to fetch the new Email
immediately.

1.6. Ids

If a JMAP Mail server also provides an IMAP interface to the data and
supports IMAP Extension for Object Identifiers [RFC8474], the ids
SHOULD be the same for Mailbox, Thread, and Email objects in JMAP.

2. Mailboxes

A Mailbox represents a named set of Email objects. This is the
primary mechanism for organising messages within an account. It is
analogous to a folder or a label in other systems. A Mailbox may
perform a certain role in the system; see below for more details.

For compatibility with IMAP, an Email MUST belong to one or more
Mailboxes. The Email id does not change if the Email changes
Mailboxes.

A *Mailbox* object has the following properties:

o id: "Id" (immutable; server-set)

The id of the Mailbox.

o name: "String"

User-visible name for the Mailbox, e.g., "Inbox". This MUST be a
Net-Unicode string [RFC5198] of at least 1 character in length,
subject to the maximum size given in the capability object. There
MUST NOT be two sibling Mailboxes with both the same parent and
the same name. Servers MAY reject names that violate server
policy (e.g., names containing a slash (/) or control characters).

o parentId: "Id|null" (default: null)
The Mailbox id for the parent of this Mailbox, or null if this
Mailbox is at the top level. Mailboxes form acyclic graphs
(forests) directed by the child-to-parent relationship. There
MUST NOT be a loop.

o role: "String|null" (default: null)

Identifies Mailboxes that have a particular common purpose (e.g.,
the "inbox"), regardless of the "name" property (which may be
localised).

This value is shared with IMAP (exposed in IMAP via the SPECIAL-
USE extension [RFC6154]). However, unlike in IMAP, a Mailbox MUST
only have a single role, and there MUST NOT be two Mailboxes in
the same account with the same role. Servers providing IMAP
access to the same data are encouraged to enforce these extra
restrictions in IMAP as well. Otherwise, modifying the IMAP
attributes to ensure compliance when exposing the data over JMAP
is implementation dependent.

The value MUST be one of the Mailbox attribute names listed in the
IANA "IMAP Mailbox Name Attributes" registry at
<https://www.iana.org/assignments/imap-mailbox-name-attributes/>,
as established in [RFC8457], converted to lowercase. New roles
may be established here in the future.

An account is not required to have Mailboxes with any particular
roles.

o sortOrder: "UnsignedInt" (default: 0)

Defines the sort order of Mailboxes when presented in the client's
UI, so it is consistent between devices. The number MUST be an
integer in the range 0 <= sortOrder < 2^31.

A Mailbox with a lower order should be displayed before a Mailbox
with a higher order (that has the same parent) in any Mailbox
listing in the client's UI. Mailboxes with equal order SHOULD be
sorted in alphabetical order by name. The sorting should take
into account locale-specific character order convention.

o totalEmails: "UnsignedInt" (server-set)

The number of Emails in this Mailbox.

o unreadEmails: "UnsignedInt" (server-set)
The number of Emails in this Mailbox that have neither the "$seen"
keyword nor the "$draft" keyword.

o totalThreads: "UnsignedInt" (server-set)

The number of Threads where at least one Email in the Thread is in
this Mailbox.

o unreadThreads: "UnsignedInt" (server-set)

An indication of the number of "unread" Threads in the Mailbox.

For compatibility with existing implementations, the way "unread
Threads" is determined is not mandated in this document. The
simplest solution to implement is simply the number of Threads
where at least one Email in the Thread is both in this Mailbox and
has neither the "$seen" nor "$draft" keywords.

However, a quality implementation will return the number of unread
items the user would see if they opened that Mailbox. A Thread is
shown as unread if it contains any unread Emails that will be
displayed when the Thread is opened. Therefore, "unreadThreads"
should be the number of Threads where at least one Email in the
Thread has neither the "$seen" nor the "$draft" keyword AND at
least one Email in the Thread is in this Mailbox. Note that the
unread Email does not need to be the one in this Mailbox. In
addition, the trash Mailbox (that is, a Mailbox whose "role" is
"trash") requires special treatment:

1. Emails that are *only* in the trash (and no other Mailbox) are
ignored when calculating the "unreadThreads" count of other
Mailboxes.

2. Emails that are *not* in the trash are ignored when
calculating the "unreadThreads" count for the trash Mailbox.

The result of this is that Emails in the trash are treated as
though they are in a separate Thread for the purposes of unread
counts. It is expected that clients will hide Emails in the trash
when viewing a Thread in another Mailbox, and vice versa. This
allows you to delete a single Email to the trash out of a Thread.

For example, suppose you have an account where the entire contents
is a single Thread with 2 Emails: an unread Email in the trash and
a read Email in the inbox. The "unreadThreads" count would be 1
for the trash and 0 for the inbox.

o myRights: "MailboxRights" (server-set)
The set of rights (Access Control Lists (ACLs)) the user has in
relation to this Mailbox. These are backwards compatible with
IMAP ACLs, as defined in [RFC4314]. A *MailboxRights* object has
the following properties:

* mayReadItems: "Boolean"

If true, the user may use this Mailbox as part of a filter in
an "Email/query" call, and the Mailbox may be included in the
"mailboxIds" property of Email objects. Email objects may be
fetched if they are in *at least one* Mailbox with this
permission. If a sub-Mailbox is shared but not the parent
Mailbox, this may be false. Corresponds to IMAP ACLs "lr" (if
mapping from IMAP, both are required for this to be true).

* mayAddItems: "Boolean"

The user may add mail to this Mailbox (by either creating a new
Email or moving an existing one). Corresponds to IMAP ACL "i".

* mayRemoveItems: "Boolean"

The user may remove mail from this Mailbox (by either changing
the Mailboxes of an Email or destroying the Email).
Corresponds to IMAP ACLs "te" (if mapping from IMAP, both are
required for this to be true).

* maySetSeen: "Boolean"

The user may add or remove the "$seen" keyword to/from an
Email. If an Email belongs to multiple Mailboxes, the user may
only modify "$seen" if they have this permission for *all* of
the Mailboxes. Corresponds to IMAP ACL "s".

* maySetKeywords: "Boolean"

The user may add or remove any keyword other than "$seen" to/
from an Email. If an Email belongs to multiple Mailboxes, the
user may only modify keywords if they have this permission for
*all* of the Mailboxes. Corresponds to IMAP ACL "w".

* mayCreateChild: "Boolean"

The user may create a Mailbox with this Mailbox as its parent.
Corresponds to IMAP ACL "k".

* mayRename: "Boolean"
The user may rename the Mailbox or make it a child of another
Mailbox. Corresponds to IMAP ACL "x" (although this covers
both rename and delete permissions).

* mayDelete: "Boolean"

The user may delete the Mailbox itself. Corresponds to IMAP
ACL "x" (although this covers both rename and delete
permissions).

* maySubmit: "Boolean"

Messages may be submitted directly to this Mailbox.
Corresponds to IMAP ACL "p".

o isSubscribed: "Boolean"

Has the user indicated they wish to see this Mailbox in their
client? This SHOULD default to false for Mailboxes in shared
accounts the user has access to and true for any new Mailboxes
created by the user themself. This MUST be stored separately per
user where multiple users have access to a shared Mailbox.

A user may have permission to access a large number of shared
accounts, or a shared account with a very large set of Mailboxes,
but only be interested in the contents of a few of these. Clients
may choose to only display Mailboxes where the "isSubscribed"
property is set to true, and offer a separate UI to allow the user
to see and subscribe/unsubscribe from the full set of Mailboxes.
However, clients MAY choose to ignore this property, either
entirely for ease of implementation or just for an account where
"isPersonal" is true (indicating it is the user's own rather than
a shared account).

This property corresponds to IMAP [RFC3501] mailbox subscriptions.

For IMAP compatibility, an Email in both the trash and another
Mailbox SHOULD be treated by the client as existing in both places
(i.e., when emptying the trash, the client should just remove it from
the trash Mailbox and leave it in the other Mailbox).

The following JMAP methods are supported.

2.1. Mailbox/get

Standard

This is a standard "/get" method as described in [RFC8620],
Section 5.1. The "ids" argument may be "null" to fetch all at once.

2.2. Mailbox/changes

Standard

This is a standard "/changes" method as described in [RFC8620],
Section 5.2 but with one extra argument to the response:

o updatedProperties: "String[]|null"

If only the "totalEmails", "unreadEmails", "totalThreads", and/or
"unreadThreads" Mailbox properties have changed since the old
state, this will be the list of properties that may have changed.
If the server is unable to tell if only counts have changed, it
MUST just be null.

Since counts frequently change but other properties are generally
only changed rarely, the server can help the client optimise data
transfer by keeping track of changes to Email/Thread counts separate
from other state changes. The "updatedProperties" array may be used
directly via a back-reference in a subsequent "Mailbox/get" call in
the same request, so only these properties are returned if nothing
else has changed.

2.3. Mailbox/query

Standard

This is a standard "/query" method as described in [RFC8620],
Section 5.5 but with the following additional request argument:

o sortAsTree: "Boolean" (default: false)

If true, when sorting the query results and comparing Mailboxes A
and B:

* If A is an ancestor of B, it always comes first regardless of
the sort comparators. Similarly, if A is descendant of B, then
B always comes first.

* Otherwise, if A and B do not share a "parentId", find the
nearest ancestors of each that do have the same "parentId" and
compare the sort properties on those Mailboxes instead.

The result of this is that the Mailboxes are sorted as a tree
according to the parentId properties, with each set of children
with a common parent sorted according to the standard sort
comparators.

o filterAsTree: "Boolean" (default: false)

If true, a Mailbox is only included in the query if all its
ancestors are also included in the query according to the filter.

A *FilterCondition* object has the following properties, any of which
may be omitted:

o parentId: "Id|null"

The Mailbox "parentId" property must match the given value
exactly.

o name: "String"

The Mailbox "name" property contains the given string.

o role: "String|null"

The Mailbox "role" property must match the given value exactly.

o hasAnyRole: "Boolean"

If true, a Mailbox matches if it has any non-null value for its
"role" property.

o isSubscribed: "Boolean"

The "isSubscribed" property of the Mailbox must be identical to
the value given to match the condition.

A Mailbox object matches the FilterCondition if and only if all of
the given conditions match. If zero properties are specified, it is
automatically true for all objects.

The following Mailbox properties MUST be supported for sorting:

o "sortOrder"

o "name"

2.4. Mailbox/queryChanges

Standard

This is a standard "/queryChanges" method as described in [RFC8620],
Section 5.6.

2.5. Mailbox/set

Standard

This is a standard "/set" method as described in [RFC8620],
Section 5.3 but with the following additional request argument:

o onDestroyRemoveEmails: "Boolean" (default: false)
If false, any attempt to destroy a Mailbox that still has Emails
in it will be rejected with a "mailboxHasEmail" SetError. If
true, any Emails that were in the Mailbox will be removed from it,
and if in no other Mailboxes, they will be destroyed when the
Mailbox is destroyed.

The following extra SetError types are defined:

For "destroy":

o "mailboxHasChild": The Mailbox still has at least one child
Mailbox. The client MUST remove these before it can delete the
parent Mailbox.

o "mailboxHasEmail": The Mailbox has at least one Email assigned to
it, and the "onDestroyRemoveEmails" argument was false.

2.6. Example

Fetching all Mailboxes in an account:

[[ "Mailbox/get", {
"accountId": "u33084183",
"ids": null
}, "0" ]]

And the response:

[[ "Mailbox/get", {
"accountId": "u33084183",
"state": "78540",
"list": [{
"id": "MB23cfa8094c0f41e6",
"name": "Inbox",
"parentId": null,
"role": "inbox",
"sortOrder": 10,
"totalEmails": 16307,
"unreadEmails": 13905,
"totalThreads": 5833,
"unreadThreads": 5128,
"myRights": {
"mayAddItems": true,
"mayRename": false,
"maySubmit": true,
"mayDelete": false,
"maySetKeywords": true,
"mayRemoveItems": true,
"mayCreateChild": true,
"maySetSeen": true,
"mayReadItems": true
},
"isSubscribed": true
}, {
"id": "MB674cc24095db49ce",
"name": "Important mail",
...
}, ... ],
"notFound": []
}, "0" ]]

Now suppose an Email is marked read, and we get a push update that
the Mailbox state has changed. You might fetch the updates like
this:

[[ "Mailbox/changes", {
"accountId": "u33084183",
"sinceState": "78540"
}, "0" ],
[ "Mailbox/get", {
"accountId": "u33084183",
"#ids": {
"resultOf": "0",
"name": "Mailbox/changes",
"path": "/created"
}
}, "1" ],
[ "Mailbox/get", {
"accountId": "u33084183",
"#ids": {
"resultOf": "0",
"name": "Mailbox/changes",
"path": "/updated"
},
"#properties": {
"resultOf": "0",
"name": "Mailbox/changes",
"path": "/updatedProperties"
}
}, "2" ]]

This fetches the list of ids for created/updated/destroyed Mailboxes,
then using back-references, it fetches the data for just the created/
updated Mailboxes in the same request. The response may look
something like this:

[[ "Mailbox/changes", {
"accountId": "u33084183",
"oldState": "78541",
"newState": "78542",
"hasMoreChanges": false,
"updatedProperties": [
"totalEmails", "unreadEmails",
"totalThreads", "unreadThreads"
],
"created": [],
"updated": ["MB23cfa8094c0f41e6"],
"destroyed": []
}, "0" ],
[ "Mailbox/get", {
"accountId": "u33084183",
"state": "78542",
"list": [],
"notFound": []
}, "1" ],
[ "Mailbox/get", {
"accountId": "u33084183",
"state": "78542",
"list": [{
"id": "MB23cfa8094c0f41e6",
"totalEmails": 16307,
"unreadEmails": 13903,
"totalThreads": 5833,
"unreadThreads": 5127
}],
"notFound": []
}, "2" ]]

Here's an example where we try to rename one Mailbox and destroy
another:

[[ "Mailbox/set", {
"accountId": "u33084183",
"ifInState": "78542",
"update": {
"MB674cc24095db49ce": {
"name": "Maybe important mail"
}
},
"destroy": [ "MB23cfa8094c0f41e6" ]
}, "0" ]]

Suppose the rename succeeds, but we don't have permission to destroy
the Mailbox we tried to destroy; we might get back:

[[ "Mailbox/set", {
"accountId": "u33084183",
"oldState": "78542",
"newState": "78549",
"updated": {
"MB674cc24095db49ce": null
},
"notDestroyed": {
"MB23cfa8094c0f41e6": {
"type": "forbidden"
}
}
}, "0" ]]

3. Threads

Replies are grouped together with the original message to form a
Thread. In JMAP, a Thread is simply a flat list of Emails, ordered
by date. Every Email MUST belong to a Thread, even if it is the only
Email in the Thread.

The exact algorithm for determining whether two Emails belong to the
same Thread is not mandated in this spec to allow for compatibility
with different existing systems. For new implementations, it is
suggested that two messages belong in the same Thread if both of the
following conditions apply:

1. An identical message id [RFC5322] appears in both messages in any
of the Message-Id, In-Reply-To, and References header fields.

2. After stripping automatically added prefixes such as "Fwd:",
"Re:", "[List-Tag]", etc., and ignoring white space, the subjects
are the same. This avoids the situation where a person replies
to an old message as a convenient way of finding the right
recipient to send to but changes the subject and starts a new
conversation.

If messages are delivered out of order for some reason, a user may
have two Emails in the same Thread but without headers that associate
them with each other. The arrival of a third Email may provide the
missing references to join them all together into a single Thread.
Since the "threadId" of an Email is immutable, if the server wishes
to merge the Threads, it MUST handle this by deleting and reinserting
(with a new Email id) the Emails that change "threadId".

A *Thread* object has the following properties:

o id: "Id" (immutable; server-set)
The id of the Thread.

o emailIds: "Id[]" (server-set)

The ids of the Emails in the Thread, sorted by the "receivedAt"
date of the Email, oldest first. If two Emails have an identical
date, the sort is server dependent but MUST be stable (sorting by
id is recommended).

The following JMAP methods are supported.

3.1. Thread/get

Standard

This is a standard "/get" method as described in [RFC8620],
Section 5.1.

3.1.1. Example

Request:

[[ "Thread/get", {
"accountId": "acme",
"ids": ["f123u4", "f41u44"]
}, "#1" ]]

with response:

[[ "Thread/get", {
"accountId": "acme",
"state": "f6a7e214",
"list": [
{
"id": "f123u4",
"emailIds": [ "eaa623", "f782cbb"]
},
{
"id": "f41u44",
"emailIds": [ "82cf7bb" ]
}
],
"notFound": []
}, "#1" ]]

3.2. Thread/changes

Standard

This is a standard "/changes" method as described in [RFC8620],
Section 5.2.

4. Emails

An *Email* object is a representation of a message [RFC5322], which
allows clients to avoid the complexities of MIME parsing, transfer
encoding, and character encoding.

4.1. Properties of the Email Object

Broadly, a message consists of two parts: a list of header fields and
then a body. The Email data type provides a way to access the full
structure or to use simplified properties and avoid some complexity
if this is sufficient for the client application.

While raw headers can be fetched and set, the vast majority of
clients should use an appropriate parsed form for each of the header
fields it wants to process, as this allows it to avoid the
complexities of various encodings that are required in a valid
message per RFC 5322.

The body of a message is normally a MIME-encoded set of documents in
a tree structure. This may be arbitrarily nested, but the majority
of email clients present a flat model of a message body (normally
plaintext or HTML) with a set of attachments. Flattening the MIME
structure to form this model can be difficult and causes
inconsistency between clients. Therefore, in addition to the
"bodyStructure" property, which gives the full tree, the Email object
contains 3 alternate properties with flat lists of body parts:

o "textBody"/"htmlBody": These provide a list of parts that should
be rendered sequentially as the "body" of the message. This is a
list rather than a single part as messages may have headers and/or
footers appended/prepended as separate parts when they are
transmitted, and some clients send text and images intended to be
displayed inline in the body (or even videos and sound clips) as
multiple parts rather than a single HTML part with referenced
images.

Because MIME allows for multiple representations of the same data
(using "multipart/alternative"), there is a "textBody" property
(which prefers a plaintext representation) and an "htmlBody"
property (which prefers an HTML representation) to accommodate the
two most common client requirements. The same part may appear in
both lists where there is no alternative between the two.

o "attachments": This provides a list of parts that should be
presented as "attachments" to the message. Some images may be
solely there for embedding within an HTML body part; clients may
wish to not present these as attachments in the user interface if
they are displaying the HTML with the embedded images directly.
Some parts may also be in htmlBody/textBody; again, clients may
wish to not present these as attachments in the user interface if
rendered as part of the body.

The "bodyValues" property allows for clients to fetch the value of
text parts directly without having to do a second request for the
blob and to have the server handle decoding the charset into unicode.
This data is in a separate property rather than on the EmailBodyPart
object to avoid duplication of large amounts of data, as the same
part may be included twice if the client fetches more than one of
bodyStructure, textBody, and htmlBody.

In the following subsections, the common notational convention for
wildcards has been adopted for content types, so "foo/*" means any
content type that starts with "foo/".

Due to the number of properties involved, the set of Email properties
is specified over the following four subsections. This is purely for
readability; all properties are top-level peers.

4.1.1. Metadata

These properties represent metadata about the message in the mail
store and are not derived from parsing the message itself.

o id: "Id" (immutable; server-set)

The id of the Email object. Note that this is the JMAP object id,
NOT the Message-ID header field value of the message [RFC5322].

o blobId: "Id" (immutable; server-set)

The id representing the raw octets of the message [RFC5322] for
this Email. This may be used to download the raw original message
or to attach it directly to another Email, etc.

o threadId: "Id" (immutable; server-set)

The id of the Thread to which this Email belongs.

o mailboxIds: "Id[Boolean]"

The set of Mailbox ids this Email belongs to. An Email in the
mail store MUST belong to one or more Mailboxes at all times
(until it is destroyed). The set is represented as an object,
with each key being a Mailbox id. The value for each key in the
object MUST be true.

o keywords: "String[Boolean]" (default: {})

A set of keywords that apply to the Email. The set is represented
as an object, with the keys being the keywords. The value for
each key in the object MUST be true.

Keywords are shared with IMAP. The six system keywords from IMAP
get special treatment. The following four keywords have their
first character changed from "\" in IMAP to "$" in JMAP and have
particular semantic meaning:

* "$draft": The Email is a draft the user is composing.

* "$seen": The Email has been read.

* "$flagged": The Email has been flagged for urgent/special
attention.

* "$answered": The Email has been replied to.

The IMAP "\Recent" keyword is not exposed via JMAP. The IMAP
"\Deleted" keyword is also not present: IMAP uses a delete+expunge
model, which JMAP does not. Any message with the "\Deleted"
keyword MUST NOT be visible via JMAP (and so are not counted in
the "totalEmails", "unreadEmails", "totalThreads", and
"unreadThreads" Mailbox properties).

Users may add arbitrary keywords to an Email. For compatibility
with IMAP, a keyword is a case-insensitive string of 1-255
characters in the ASCII subset %x21-%x7e (excludes control chars
and space), and it MUST NOT include any of these characters:

( ) { ] % * " \

Because JSON is case sensitive, servers MUST return keywords in
lowercase.

The IANA "IMAP and JMAP Keywords" registry at
<https://www.iana.org/assignments/imap-jmap-keywords/> as
established in [RFC5788] assigns semantic meaning to some other
keywords in common use. New keywords may be established here in
the future. In particular, note:

* "$forwarded": The Email has been forwarded.

* "$phishing": The Email is highly likely to be phishing.
Clients SHOULD warn users to take care when viewing this Email
and disable links and attachments.

* "$junk": The Email is definitely spam. Clients SHOULD set this
flag when users report spam to help train automated spam-
detection systems.

* "$notjunk": The Email is definitely not spam. Clients SHOULD
set this flag when users indicate an Email is legitimate, to
help train automated spam-detection systems.

o size: "UnsignedInt" (immutable; server-set)

The size, in octets, of the raw data for the message [RFC5322] (as
referenced by the "blobId", i.e., the number of octets in the file
the user would download).

o receivedAt: "UTCDate" (immutable; default: time of creation on
server)

The date the Email was received by the message store. This is the
"internal date" in IMAP [RFC3501].

4.1.2. Header Fields Parsed Forms

Header field properties are derived from the message header fields
[RFC5322] [RFC6532]. All header fields may be fetched in a raw form.
Some header fields may also be fetched in a parsed form. The
structured form that may be fetched depends on the header. The forms
are defined in the subsections that follow.

4.1.2.1. Raw

Type: "String"

The raw octets of the header field value from the first octet
following the header field name terminating colon, up to but
excluding the header field terminating CRLF. Any standards-compliant
message MUST be either ASCII (RFC 5322) or UTF-8 (RFC 6532); however,
other encodings exist in the wild. A server SHOULD replace any octet
or octet run with the high bit set that violates UTF-8 syntax with
the unicode replacement character (U+FFFD). Any NUL octet MUST be
dropped.

This form will typically have a leading space, as most generated
messages insert a space after the colon that terminates the header
field name.

4.1.2.2. Text

Type: "String"

The header field value with:

1. White space unfolded (as defined in [RFC5322], Section 2.2.3).

2. The terminating CRLF at the end of the value removed.

3. Any SP characters at the beginning of the value removed.

4. Any syntactically correct encoded sections [RFC2047] with a known
character set decoded. Any NUL octets or control characters
encoded per [RFC2047] are dropped from the decoded value. Any
text that looks like syntax per [RFC2047] but violates placement
or white space rules per [RFC2047] MUST NOT be decoded.

5. The resulting unicode converted to Normalization Form C (NFC)
form.

If any decodings fail, the parser SHOULD insert a unicode replacement
character (U+FFFD) and attempt to continue as much as possible.

To prevent obviously nonsense behaviour, which can lead to
interoperability issues, this form may only be fetched or set for the
following header fields:

o Subject

o Comments

o Keywords

o List-Id

o Any header field not defined in [RFC5322] or [RFC2369]

4.1.2.3. Addresses

Type: "EmailAddress[]"

The header field is parsed as an "address-list" value, as specified
in [RFC5322], Section 3.4, into the "EmailAddress[]" type. There is
an EmailAddress item for each "mailbox" parsed from the "address-
list". Group and comment information is discarded.

An *EmailAddress* object has the following properties:

o name: "String|null"

The "display-name" of the "mailbox" [RFC5322]. If this is a
"quoted-string":

1. The surrounding DQUOTE characters are removed.

2. Any "quoted-pair" is decoded.

3. White space is unfolded, and then any leading and trailing
white space is removed.

If there is no "display-name" but there is a "comment" immediately
following the "addr-spec", the value of this SHOULD be used
instead. Otherwise, this property is null.

o email: "String"

The "addr-spec" of the "mailbox" [RFC5322].

Any syntactically correct encoded sections [RFC2047] with a known
encoding MUST be decoded, following the same rules as for the Text
form (see Section 4.1.2.2).

Parsing SHOULD be best effort in the face of invalid structure to
accommodate invalid messages and semi-complete drafts. EmailAddress
objects MAY have an "email" property that does not conform to the
"addr-spec" form (for example, may not contain an @ symbol).

For example, the following "address-list" string:

" James Smythe" <james@example.com>, Friends:
jane@example.com, =?UTF-8?Q?John_Sm=C3=AEth?=
<john@example.com>;

would be parsed as:

[
{ "name": "James Smythe", "email": "james@example.com" },
{ "name": null, "email": "jane@example.com" },
{ "name": "John Smith", "email": "john@example.com" }
]

To prevent obviously nonsense behaviour, which can lead to
interoperability issues, this form may only be fetched or set for the
following header fields:

o From
o Sender

o Reply-To

o To

o Cc

o Bcc

o Resent-From

o Resent-Sender

o Resent-Reply-To

o Resent-To

o Resent-Cc

o Resent-Bcc

o Any header field not defined in [RFC5322] or [RFC2369]

4.1.2.4. GroupedAddresses

Type: "EmailAddressGroup[]"

This is similar to the Addresses form but preserves group
information. The header field is parsed as an "address-list" value,
as specified in [RFC5322], Section 3.4, into the "GroupedAddresses[]"
type. Consecutive "mailbox" values that are not part of a group are
still collected under an EmailAddressGroup object to provide a
uniform type.

An *EmailAddressGroup* object has the following properties:

o name: "String|null"

The "display-name" of the "group" [RFC5322], or null if the
addresses are not part of a group. If this is a "quoted-string",
it is processed the same as the "name" in the EmailAddress type.

o addresses: "EmailAddress[]"

The "mailbox" values that belong to this group, represented as
EmailAddress objects.

Any syntactically correct encoded sections [RFC2047] with a known
encoding MUST be decoded, following the same rules as for the Text
form (see Section 4.1.2.2).

Parsing SHOULD be best effort in the face of invalid structure to
accommodate invalid messages and semi-complete drafts.

For example, the following "address-list" string:

" James Smythe" <james@example.com>, Friends:
jane@example.com, =?UTF-8?Q?John_Sm=C3=AEth?=
<john@example.com>;

would be parsed as:

[
{ "name": null, "addresses": [
{ "name": "James Smythe", "email": "james@example.com" }
]},
{ "name": "Friends", "addresses": [
{ "name": null, "email": "jane@example.com" },
{ "name": "John Smith", "email": "john@example.com" }
]}
]

To prevent obviously nonsense behaviour, which can lead to
interoperability issues, this form may only be fetched or set for the
same header fields as the Addresses form (see Section 4.1.2.3).

4.1.2.5. MessageIds

Type: "String[]|null"

The header field is parsed as a list of "msg-id" values, as specified
in [RFC5322], Section 3.6.4, into the "String[]" type. Comments and/
or folding white space (CFWS) and surrounding angle brackets ("<>")
are removed. If parsing fails, the value is null.

To prevent obviously nonsense behaviour, which can lead to
interoperability issues, this form may only be fetched or set for the
following header fields:

o Message-ID

o In-Reply-To

o References
o Resent-Message-ID

o Any header field not defined in [RFC5322] or [RFC2369]

4.1.2.6. Date

Type: "Date|null"

The header field is parsed as a "date-time" value, as specified in
[RFC5322], Section 3.3, into the "Date" type. If parsing fails, the
value is null.

To prevent obviously nonsense behaviour, which can lead to
interoperability issues, this form may only be fetched or set for the
following header fields:

o Date

o Resent-Date

o Any header field not defined in [RFC5322] or [RFC2369]

4.1.2.7. URLs

Type: "String[]|null"

The header field is parsed as a list of URLs, as described in
[RFC2369], into the "String[]" type. Values do not include the
surrounding angle brackets or any comments in the header field with
the URLs. If parsing fails, the value is null.

To prevent obviously nonsense behaviour, which can lead to
interoperability issues, this form may only be fetched or set for the
following header fields:

o List-Help

o List-Unsubscribe

o List-Subscribe

o List-Post

o List-Owner

o List-Archive

o Any header field not defined in [RFC5322] or [RFC2369]

4.1.3. Header Fields Properties

The following low-level Email property is specified for complete
access to the header data of the message:

o headers: "EmailHeader[]" (immutable)

This is a list of all header fields [RFC5322], in the same order
they appear in the message. An *EmailHeader* object has the
following properties:

* name: "String"

The header "field name" as defined in [RFC5322], with the same
capitalization that it has in the message.

* value: "String"

The header "field value" as defined in [RFC5322], in Raw form.

In addition, the client may request/send properties representing
individual header fields of the form:

header:{header-field-name}

Where "{header-field-name}" means any series of one or more printable
ASCII characters (i.e., characters that have values between 33 and
126, inclusive), except for colon (:). The property may also have
the following suffixes:

o :as{header-form}

This means the value is in a parsed form, where "{header-form}" is
one of the parsed-form names specified above. If not given, the
value is in Raw form.

o :all

This means the value is an array, with the items corresponding to
each instance of the header field, in the order they appear in the
message. If this suffix is not used, the result is the value of
the *last* instance of the header field (i.e., identical to the
last item in the array if :all is used), or null if none.

If both suffixes are used, they MUST be specified in the order above.
Header field names are matched case insensitively. The value is
typed according to the requested form or to an array of that type if
:all is used. If no header fields exist in the message with the
requested name, the value is null if fetching a single instance or an
empty array if requesting :all.

As a simple example, if the client requests a property called
"header:subject", this means find the *last* header field in the
message named "subject" (matched case insensitively) and return the
value in Raw form, or null if no header field of this name is found.

For a more complex example, consider the client requesting a property
called "header:Resent-To:asAddresses:all". This means:

1. Find *all* header fields named Resent-To (matched case
insensitively).

2. For each instance, parse the header field value in the Addresses
form.

3. The result is of type "EmailAddress[][]" -- each item in the
array corresponds to the parsed value (which is itself an array)
of the Resent-To header field instance.

The following convenience properties are also specified for the Email
object:

o messageId: "String[]|null" (immutable)

The value is identical to the value of "header:Message-
ID:asMessageIds". For messages conforming to RFC 5322, this will
be an array with a single entry.

o inReplyTo: "String[]|null" (immutable)

The value is identical to the value of "header:In-Reply-
To:asMessageIds".

o references: "String[]|null" (immutable)

The value is identical to the value of
"header:References:asMessageIds".

o sender: "EmailAddress[]|null" (immutable)

The value is identical to the value of
"header:Sender:asAddresses".

o from: "EmailAddress[]|null" (immutable)

The value is identical to the value of "header:From:asAddresses".

o to: "EmailAddress[]|null" (immutable)

The value is identical to the value of "header:To:asAddresses".

o cc: "EmailAddress[]|null" (immutable)

The value is identical to the value of "header:Cc:asAddresses".

o bcc: "EmailAddress[]|null" (immutable)

The value is identical to the value of "header:Bcc:asAddresses".

o replyTo: "EmailAddress[]|null" (immutable)

The value is identical to the value of "header:Reply-
To:asAddresses".

o subject: "String|null" (immutable)

The value is identical to the value of "header:Subject:asText".

o sentAt: "Date|null" (immutable; default on creation: current
server time)

The value is identical to the value of "header:Date:asDate".

4.1.4. Body Parts

These properties are derived from the message body [RFC5322] and its
MIME entities [RFC2045].

An *EmailBodyPart* object has the following properties:

o partId: "String|null"

Identifies this part uniquely within the Email. This is scoped to
the "emailId" and has no meaning outside of the JMAP Email object
representation. This is null if, and only if, the part is of type
"multipart/*".

o blobId: "Id|null"

The id representing the raw octets of the contents of the part,
after decoding any known Content-Transfer-Encoding (as defined in
[RFC2045]), or null if, and only if, the part is of type
"multipart/*". Note that two parts may be transfer-encoded
differently but have the same blob id if their decoded octets are
identical and the server is using a secure hash of the data for
the blob id. If the transfer encoding is unknown, it is treated
as though it had no transfer encoding.

o size: "UnsignedInt"

The size, in octets, of the raw data after content transfer
decoding (as referenced by the "blobId", i.e., the number of
octets in the file the user would download).

o headers: "EmailHeader[]"

This is a list of all header fields in the part, in the order they
appear in the message. The values are in Raw form.

o name: "String|null"

This is the decoded "filename" parameter of the Content-
Disposition header field per [RFC2231], or (for compatibility with
existing systems) if not present, then it's the decoded "name"
parameter of the Content-Type header field per [RFC2047].

o type: "String"

The value of the Content-Type header field of the part, if
present; otherwise, the implicit type as per the MIME standard
("text/plain" or "message/rfc822" if inside a "multipart/digest").
CFWS is removed and any parameters are stripped.

o charset: "String|null"

The value of the charset parameter of the Content-Type header
field, if present, or null if the header field is present but not
of type "text/*". If there is no Content-Type header field, or it
exists and is of type "text/*" but has no charset parameter, this
is the implicit charset as per the MIME standard: "us-ascii".

o disposition: "String|null"

The value of the Content-Disposition header field of the part, if
present; otherwise, it's null. CFWS is removed and any parameters
are stripped.

o cid: "String|null"

The value of the Content-Id header field of the part, if present;
otherwise, it's null. CFWS and surrounding angle brackets ("<>")
are removed. This may be used to reference the content from
within a "text/html" body part [HTML] using the "cid:" protocol,
as defined in [RFC2392].

o language: "String[]|null"

The list of language tags, as defined in [RFC3282], in the
Content-Language header field of the part, if present.

o location: "String|null"

The URI, as defined in [RFC2557], in the Content-Location header
field of the part, if present.

o subParts: "EmailBodyPart[]|null"

If the type is "multipart/*", this contains the body parts of each
child.

In addition, the client may request/send EmailBodyPart properties
representing individual header fields, following the same syntax and
semantics as for the Email object, e.g., "header:Content-Type".

The following Email properties are specified for access to the body
data of the message:

o bodyStructure: "EmailBodyPart" (immutable)

This is the full MIME structure of the message body, without
recursing into "message/rfc822" or "message/global" parts. Note
that EmailBodyParts may have subParts if they are of type
"multipart/*".

o bodyValues: "String[EmailBodyValue]" (immutable)

This is a map of "partId" to an EmailBodyValue object for none,
some, or all "text/*" parts. Which parts are included and whether
the value is truncated is determined by various arguments to
"Email/get" and "Email/parse". An *EmailBodyValue* object has the
following properties:

* value: "String"

The value of the body part after decoding Content-Transfer-
Encoding and the Content-Type charset, if both known to the
server, and with any CRLF replaced with a single LF. The
server MAY use heuristics to determine the charset to use for
decoding if the charset is unknown, no charset is given, or it
believes the charset given is incorrect. Decoding is best
effort; the server SHOULD insert the unicode replacement
character (U+FFFD) and continue when a malformed section is
encountered.

Note that due to the charset decoding and line ending
normalisation, the length of this string will probably not be
exactly the same as the "size" property on the corresponding
EmailBodyPart.

* isEncodingProblem: "Boolean" (default: false)

This is true if malformed sections were found while decoding
the charset, the charset was unknown, or the content-transfer-
encoding was unknown.

* isTruncated: "Boolean" (default: false)

This is true if the "value" has been truncated.

See the Security Considerations section for issues related to
truncation and heuristic determination of the content-type and
charset.

o textBody: "EmailBodyPart[]" (immutable)

A list of "text/plain", "text/html", "image/*", "audio/*", and/or
"video/*" parts to display (sequentially) as the message body,
with a preference for "text/plain" when alternative versions are
available.

o htmlBody: "EmailBodyPart[]" (immutable)

A list of "text/plain", "text/html", "image/*", "audio/*", and/or
"video/*" parts to display (sequentially) as the message body,
with a preference for "text/html" when alternative versions are
available.

o attachments: "EmailBodyPart[]" (immutable)

A list, traversing depth-first, of all parts in "bodyStructure"
that satisfy either of the following conditions:

* not of type "multipart/*" and not included in "textBody" or
"htmlBody"

* of type "image/*", "audio/*", or "video/*" and not in both
"textBody" and "htmlBody"
None of these parts include subParts, including "message/*" types.
Attached messages may be fetched using the "Email/parse" method
and the "blobId".

Note that a "text/html" body part [HTML] may reference image parts
in attachments by using "cid:" links to reference the Content-Id,
as defined in [RFC2392], or by referencing the Content-Location.

o hasAttachment: "Boolean" (immutable; server-set)

This is true if there are one or more parts in the message that a
client UI should offer as downloadable. A server SHOULD set
hasAttachment to true if the "attachments" list contains at least
one item that does not have "Content-Disposition: inline". The
server MAY ignore parts in this list that are processed
automatically in some way or are referenced as embedded images in
one of the "text/html" parts of the message.

The server MAY set hasAttachment based on implementation-defined
or site-configurable heuristics.

o preview: "String" (immutable; server-set)

A plaintext fragment of the message body. This is intended to be
shown as a preview line when listing messages in the mail store
and may be truncated when shown. The server may choose which part
of the message to include in the preview; skipping quoted sections
and salutations and collapsing white space can result in a more
useful preview.

This MUST NOT be more than 256 characters in length.

As this is derived from the message content by the server, and the
algorithm for doing so could change over time, fetching this for
an Email a second time MAY return a different result. However,
the previous value is not considered incorrect, and the change
SHOULD NOT cause the Email object to be considered as changed by
the server.

The exact algorithm for decomposing bodyStructure into textBody,
htmlBody, and attachments part lists is not mandated, as this is a
quality-of-service implementation issue and likely to require
workarounds for malformed content discovered over time. However, the
following algorithm (expressed here in JavaScript) is suggested as a
starting point, based on real-world experience:

function isInlineMediaType ( type ) {
return type.startsWith( 'image/' ) ||
type.startsWith( 'audio/' ) ||
type.startsWith( 'video/' );
}

function parseStructure ( parts, multipartType, inAlternative,
htmlBody, textBody, attachments ) {

// For multipartType == alternative
let textLength = textBody ? textBody.length : -1;
let htmlLength = htmlBody ? htmlBody.length : -1;

for ( let i = 0; i < parts.length; i += 1 ) {
let part = parts[i];
let isMultipart = part.type.startsWith( 'multipart/' );
// Is this a body part rather than an attachment
let isInline = part.disposition != "attachment" &&
// Must be one of the allowed body types
( part.type == "text/plain" ||
part.type == "text/html" ||
isInlineMediaType( part.type ) ) &&
// If multipart/related, only the first part can be inline
// If a text part with a filename, and not the first item
// in the multipart, assume it is an attachment
( i === 0 ||
( multipartType != "related" &&
( isInlineMediaType( part.type ) || !part.name ) ) );

if ( isMultipart ) {
let subMultiType = part.type.split( '/' )[1];
parseStructure( part.subParts, subMultiType,
inAlternative || ( subMultiType == 'alternative' ),
htmlBody, textBody, attachments );
} else if ( isInline ) {
if ( multipartType == 'alternative' ) {
switch ( part.type ) {
case 'text/plain':
textBody.push( part );
break;
case 'text/html':
htmlBody.push( part );
break;
default:
attachments.push( part );
break;
}
continue;
} else if ( inAlternative ) {
if ( part.type == 'text/plain' ) {
htmlBody = null;
}
if ( part.type == 'text/html' ) {
textBody = null;
}
}
if ( textBody ) {
textBody.push( part );
}
if ( htmlBody ) {
htmlBody.push( part );
}
if ( ( !textBody || !htmlBody ) &&
isInlineMediaType( part.type ) ) {
attachments.push( part );
}
} else {
attachments.push( part );
}
}

if ( multipartType == 'alternative' && textBody && htmlBody ) {
// Found HTML part only
if ( textLength == textBody.length &&
htmlLength != htmlBody.length ) {
for ( let i = htmlLength; i < htmlBody.length; i += 1 ) {
textBody.push( htmlBody[i] );
}
}
// Found plaintext part only
if ( htmlLength == htmlBody.length &&
textLength != textBody.length ) {
for ( let i = textLength; i < textBody.length; i += 1 ) {
htmlBody.push( textBody[i] );
}
}
}
}

// Usage:
let htmlBody = [];
let textBody = [];
let attachments = [];

parseStructure( [ bodyStructure ], 'mixed', false,
htmlBody, textBody, attachments );
For instance, consider a message with both text and HTML versions
that has gone through a list software manager that attaches a header
and footer. It might have a MIME structure something like:

multipart/mixed
text/plain, content-disposition=inline - A
multipart/mixed
multipart/alternative
multipart/mixed
text/plain, content-disposition=inline - B
image/jpeg, content-disposition=inline - C
text/plain, content-disposition=inline - D
multipart/related
text/html - E
image/jpeg - F
image/jpeg, content-disposition=attachment - G
application/x-excel - H
message/rfc822 - J
text/plain, content-disposition=inline - K

In this case, the above algorithm would decompose this to:

textBody => [ A, B, C, D, K ]
htmlBody => [ A, E, K ]
attachments => [ C, F, G, H, J ]

4.2. Email/get

Standard

This is a standard "/get" method as described in [RFC8620],
Section 5.1 with the following additional request arguments:

o bodyProperties: "String[]"

A list of properties to fetch for each EmailBodyPart returned. If
omitted, this defaults to:

[ "partId", "blobId", "size", "name", "type", "charset",
"disposition", "cid", "language", "location" ]

o fetchTextBodyValues: "Boolean" (default: false)

If true, the "bodyValues" property includes any "text/*" part in
the "textBody" property.

o fetchHTMLBodyValues: "Boolean" (default: false)

If true, the "bodyValues" property includes any "text/*" part in
the "htmlBody" property.

o fetchAllBodyValues: "Boolean" (default: false)

If true, the "bodyValues" property includes any "text/*" part in
the "bodyStructure" property.

o maxBodyValueBytes: "UnsignedInt" (default: 0)

If greater than zero, the "value" property of any EmailBodyValue
object returned in "bodyValues" MUST be truncated if necessary so
it does not exceed this number of octets in size. If 0 (the
default), no truncation occurs.

The server MUST ensure the truncation results in valid UTF-8 and
does not occur mid-codepoint. If the part is of type "text/html",
the server SHOULD NOT truncate inside an HTML tag, e.g., in the
middle of "<a href="https://example.com">". There is no
requirement for the truncated form to be a balanced tree or valid
HTML (indeed, the original source may well be neither of these
things).

If the standard "properties" argument is omitted or null, the
following default MUST be used instead of "all" properties:

[ "id", "blobId", "threadId", "mailboxIds", "keywords", "size",
"receivedAt", "messageId", "inReplyTo", "references", "sender", "from",
"to", "cc", "bcc", "replyTo", "subject", "sentAt", "hasAttachment",
"preview", "bodyValues", "textBody", "htmlBody", "attachments" ]

The following properties are expected to be fast to fetch in a
quality implementation:

o id

o blobId

o threadId

o mailboxIds

o keywords

o size

o receivedAt

o messageId

o inReplyTo
o sender

o from

o to

o cc

o bcc

o replyTo

o subject

o sentAt

o hasAttachment

o preview

Clients SHOULD take care when fetching any other properties, as there
may be significantly longer latency in fetching and returning the
data.

As specified above, parsed forms of headers may only be used on
appropriate header fields. Attempting to fetch a form that is
forbidden (e.g., "header:From:asDate") MUST result in the method call
being rejected with an "invalidArguments" error.

Where a specific header field is requested as a property, the
capitalization of the property name in the response MUST be identical
to that used in the request.

4.2.1. Example

Request:

[[ "Email/get", {
"ids": [ "f123u456", "f123u457" ],
"properties": [ "threadId", "mailboxIds", "from", "subject",
"receivedAt", "header:List-POST:asURLs",
"htmlBody", "bodyValues" ],
"bodyProperties": [ "partId", "blobId", "size", "type" ],
"fetchHTMLBodyValues": true,
"maxBodyValueBytes": 256
}, "#1" ]]

and response:

[[ "Email/get", {
"accountId": "abc",
"state": "41234123231",
"list": [
{
"id": "f123u457",
"threadId": "ef1314a",
"mailboxIds": { "f123": true },
"from": [{ "name": "Joe Bloggs", "email": "joe@example.com" }],
"subject": "Dinner on Thursday?",
"receivedAt": "2013-10-13T14:12:00Z",
"header:List-POST:asURLs": [
"mailto:partytime@lists.example.com"
],
"htmlBody": [{
"partId": "1",
"blobId": "B841623871",
"size": 283331,
"type": "text/html"
}, {
"partId": "2",
"blobId": "B319437193",
"size": 10343,
"type": "text/plain"
}],
"bodyValues": {
"1": {
"isEncodingProblem": false,
"isTruncated": true,
"value": "<html><body><p>Hello ..."
},
"2": {
"isEncodingProblem": false,
"isTruncated": false,
"value": "-- Sent by your friendly mailing list ..."
}
}
}
],
"notFound": [ "f123u456" ]
}, "#1" ]]

4.3. Email/changes

Standard

This is a standard "/changes" method as described in [RFC8620],
Section 5.2. If generating intermediate states for a large set of
changes, it is recommended that newer changes be returned first, as
these are generally of more interest to users.

4.4. Email/query

Standard

This is a standard "/query" method as described in [RFC8620],
Section 5.5 but with the following additional request arguments:

o collapseThreads: "Boolean" (default: false)

If true, Emails in the same Thread as a previous Email in the list
(given the filter and sort order) will be removed from the list.
This means only one Email at most will be included in the list for
any given Thread.

In quality implementations, the query "total" property is expected to
be fast to calculate when the filter consists solely of a single
"inMailbox" property, as it is the same as the totalEmails or
totalThreads properties (depending on whether collapseThreads is
true) of the associated Mailbox object.

4.4.1. Filtering

A *FilterCondition* object has the following properties, any of which
may be omitted:

o inMailbox: "Id"

A Mailbox id. An Email must be in this Mailbox to match the
condition.

o inMailboxOtherThan: "Id[]"

A list of Mailbox ids. An Email must be in at least one Mailbox
not in this list to match the condition. This is to allow
messages solely in trash/spam to be easily excluded from a search.

o before: "UTCDate"

The "receivedAt" date-time of the Email must be before this date-
time to match the condition.

o after: "UTCDate"

The "receivedAt" date-time of the Email must be the same or after
this date-time to match the condition.

o minSize: "UnsignedInt"

The "size" property of the Email must be equal to or greater than
this number to match the condition.

o maxSize: "UnsignedInt"

The "size" property of the Email must be less than this number to
match the condition.

o allInThreadHaveKeyword: "String"

All Emails (including this one) in the same Thread as this Email
must have the given keyword to match the condition.

o someInThreadHaveKeyword: "String"

At least one Email (possibly this one) in the same Thread as this
Email must have the given keyword to match the condition.

o noneInThreadHaveKeyword: "String"

All Emails (including this one) in the same Thread as this Email
must *not* have the given keyword to match the condition.

o hasKeyword: "String"

This Email must have the given keyword to match the condition.

o notKeyword: "String"

This Email must not have the given keyword to match the condition.

o hasAttachment: "Boolean"

The "hasAttachment" property of the Email must be identical to the
value given to match the condition.

o text: "String"

Looks for the text in Emails. The server MUST look up text in the
From, To, Cc, Bcc, and Subject header fields of the message and
SHOULD look inside any "text/*" or other body parts that may be
converted to text by the server. The server MAY extend the search
to any additional textual property.

o from: "String"

Looks for the text in the From header field of the message.

o to: "String"

Looks for the text in the To header field of the message.

o cc: "String"

Looks for the text in the Cc header field of the message.

o bcc: "String"

Looks for the text in the Bcc header field of the message.

o subject: "String"

Looks for the text in the Subject header field of the message.

o body: "String"

Looks for the text in one of the body parts of the message. The
server MAY exclude MIME body parts with content media types other
than "text/*" and "message/*" from consideration in search
matching. Care should be taken to match based on the text content
actually presented to an end user by viewers for that media type
or otherwise identified as appropriate for search indexing.
Matching document metadata uninteresting to an end user (e.g.,
markup tag and attribute names) is undesirable.

o header: "String[]"

The array MUST contain either one or two elements. The first
element is the name of the header field to match against. The
second (optional) element is the text to look for in the header
field value. If not supplied, the message matches simply if it
has a header field of the given name.

If zero properties are specified on the FilterCondition, the
condition MUST always evaluate to true. If multiple properties are
specified, ALL must apply for the condition to be true (it is
equivalent to splitting the object into one-property conditions and
making them all the child of an AND filter operator).

The exact semantics for matching "String" fields is *deliberately not
defined* to allow for flexibility in indexing implementation, subject
to the following:

o Any syntactically correct encoded sections [RFC2047] of header
fields with a known encoding SHOULD be decoded before attempting
to match text.

o When searching inside a "text/html" body part, any text considered
markup rather than content SHOULD be ignored, including HTML tags
and most attributes, anything inside the "<head>" tag, Cascading
Style Sheets (CSS), and JavaScript. Attribute content intended
for presentation to the user such as "alt" and "title" SHOULD be
considered in the search.

o Text SHOULD be matched in a case-insensitive manner.

o Text contained in either (but matched) single (') or double (")
quotes SHOULD be treated as a *phrase search*; that is, a match is
required for that exact word or sequence of words, excluding the
surrounding quotation marks.

Within a phrase, to match one of the following characters you MUST
escape it by prefixing it with a backslash (\):

' " \

o Outside of a phrase, white space SHOULD be treated as dividing
separate tokens that may be searched for separately but MUST all
be present for the Email to match the filter.

o Tokens (not part of a phrase) MAY be matched on a whole-word basis
using stemming (for example, a text search for "bus" would match
"buses" but not "business").

4.4.2. Sorting

The following value for the "property" field on the Comparator object
MUST be supported for sorting:

o "receivedAt" - The "receivedAt" date as returned in the Email
object.

The following values for the "property" field on the Comparator
object SHOULD be supported for sorting. When specifying a
"hasKeyword", "allInThreadHaveKeyword", or "someInThreadHaveKeyword"
sort, the Comparator object MUST also have a "keyword" property.

o "size" - The "size" as returned in the Email object.

o "from" - This is taken to be either the "name" property or if
null/empty, the "email" property of the *first* EmailAddress
object in the Email's "from" property. If still none, consider
the value to be the empty string.

o "to" - This is taken to be either the "name" property or if null/
empty, the "email" property of the *first* EmailAddress object in
the Email's "to" property. If still none, consider the value to
be the empty string.

o "subject" - This is taken to be the base subject of the message,
as defined in Section 2.1 of [RFC5256].

o "sentAt" - The "sentAt" property on the Email object.

o "hasKeyword" - This value MUST be considered true if the Email has
the keyword given as an additional "keyword" property on the
Comparator object, or false otherwise.

o "allInThreadHaveKeyword" - This value MUST be considered true for
the Email if *all* of the Emails in the same Thread have the
keyword given as an additional "keyword" property on the
Comparator object.

o "someInThreadHaveKeyword" - This value MUST be considered true for
the Email if *any* of the Emails in the same Thread have the
keyword given as an additional "keyword" property on the
Comparator object.

The server MAY support sorting based on other properties as well. A
client can discover which properties are supported by inspecting the
account's "capabilities" object (see Section 1.3).

Example sort:

[{
"property": "someInThreadHaveKeyword",
"keyword": "$flagged",
"isAscending": false
}, {
"property": "subject",
"collation": "i;ascii-casemap"
}, {
"property": "receivedAt",
"isAscending": false
}]

This would sort Emails in flagged Threads first (the Thread is
considered flagged if any Email within it is flagged), in subject
order second, and then from newest first for messages with the same
subject. If two Emails have identical values for all three
properties, then the order is server dependent but must be stable.

4.4.3. Thread Collapsing

When "collapseThreads" is true, then after filtering and sorting the
Email list, the list is further winnowed by removing any Emails for a
Thread id that has already been seen (when passing through the list
sequentially). A Thread will therefore only appear *once* in the
result, at the position of the first Email in the list that belongs
to the Thread (given the current sort/filter).

4.5. Email/queryChanges

Standard

This is a standard "/queryChanges" method as described in [RFC8620],
Section 5.6 with the following additional request argument:

o collapseThreads: "Boolean" (default: false)

The "collapseThreads" argument that was used with "Email/query".

4.6. Email/set

Standard

This is a standard "/set" method as described in [RFC8620],
Section 5.3. The "Email/set" method encompasses:

o Creating a draft

o Changing the keywords of an Email (e.g., unread/flagged status)

o Adding/removing an Email to/from Mailboxes (moving a message)

o Deleting Emails

The format of the "keywords"/"mailboxIds" properties means that when
updating an Email, you can either replace the entire set of keywords/
Mailboxes (by setting the full value of the property) or add/remove
individual ones using the JMAP patch syntax (see [RFC8620],
Section 5.3 for the specification and Section 5.7 for an example).

Due to the format of the Email object, when creating an Email, there
are a number of ways to specify the same information. To ensure that
the message [RFC5322] to create is unambiguous, the following
constraints apply to Email objects submitted for creation:

o The "headers" property MUST NOT be given on either the top-level
Email or an EmailBodyPart -- the client must set each header field
as an individual property.

o There MUST NOT be two properties that represent the same header
field (e.g., "header:from" and "from") within the Email or
particular EmailBodyPart.

o Header fields MUST NOT be specified in parsed forms that are
forbidden for that particular field.

o Header fields beginning with "Content-" MUST NOT be specified on
the Email object, only on EmailBodyPart objects.

o If a "bodyStructure" property is given, there MUST NOT be
"textBody", "htmlBody", or "attachments" properties.

o If given, the "bodyStructure" EmailBodyPart MUST NOT contain a
property representing a header field that is already defined on
the top-level Email object.

o If given, textBody MUST contain exactly one body part and it MUST
be of type "text/plain".

o If given, htmlBody MUST contain exactly one body part and it MUST
be of type "text/html".

o Within an EmailBodyPart:

* The client may specify a partId OR a blobId, but not both. If
a partId is given, this partId MUST be present in the
"bodyValues" property.

* The "charset" property MUST be omitted if a partId is given
(the part's content is included in bodyValues, and the server
may choose any appropriate encoding).

* The "size" property MUST be omitted if a partId is given. If a
blobId is given, it may be included but is ignored by the
server (the size is actually calculated from the blob content
itself).

* A Content-Transfer-Encoding header field MUST NOT be given.

o Within an EmailBodyValue object, isEncodingProblem and isTruncated
MUST be either false or omitted.

Creation attempts that violate any of this SHOULD be rejected with an
"invalidProperties" error; however, a server MAY choose to modify the
Email (e.g., choose between conflicting headers, use a different
content-encoding, etc.) to comply with its requirements instead.

The server MAY also choose to set additional headers. If not
included, the server MUST generate and set a Message-ID header field
in conformance with [RFC5322], Section 3.6.4 and a Date header field
in conformance with Section 3.6.1.

The final message generated may be invalid per RFC 5322. For
example, if it is a half-finished draft, the To header field may have
a value that does not conform to the required syntax for this header.
The message will be checked for strict conformance when submitted for
sending (see the EmailSubmission object description).

Destroying an Email removes it from all Mailboxes to which it
belonged. To just delete an Email to trash, simply change the
"mailboxIds" property, so it is now in the Mailbox with a "role"
property equal to "trash", and remove all other Mailbox ids.

When emptying the trash, clients SHOULD NOT destroy Emails that are
also in a Mailbox other than trash. For those Emails, they SHOULD
just remove the trash Mailbox from the Email.

For successfully created Email objects, the "created" response
contains the "id", "blobId", "threadId", and "size" properties of the
object.

The following extra SetError types are defined:

For "create":

o "blobNotFound": At least one blob id given for an EmailBodyPart
doesn't exist. An extra "notFound" property of type "Id[]" MUST
be included in the SetError object containing every "blobId"
referenced by an EmailBodyPart that could not be found on the
server.

For "create" and "update":

o "tooManyKeywords": The change to the Email's keywords would exceed
a server-defined maximum.

o "tooManyMailboxes": The change to the set of Mailboxes that this
Email is in would exceed a server-defined maximum.

4.7. Email/copy

Standard

This is a standard "/copy" method as described in [RFC8620],
Section 5.4, except only the "mailboxIds", "keywords", and
"receivedAt" properties may be set during the copy. This method
cannot modify the message represented by the Email.

The server MAY forbid two Email objects with identical message
content [RFC5322], or even just with the same Message-ID [RFC5322],
to coexist within an account; if the target account already has the
Email, the copy will be rejected with a standard "alreadyExists"
error.

For successfully copied Email objects, the "created" response
contains the "id", "blobId", "threadId", and "size" properties of the
new object.

4.8. Email/import

The "Email/import" method adds messages [RFC5322] to the set of
Emails in an account. The server MUST support messages with Email
Address Internationalization (EAI) headers [RFC6532]. The messages
must first be uploaded as blobs using the standard upload mechanism.
The method takes the following arguments:

o accountId: "Id"

The id of the account to use.

o ifInState: "String|null"

This is a state string as returned by the "Email/get" method. If
supplied, the string must match the current state of the account
referenced by the accountId; otherwise, the method will be aborted
and a "stateMismatch" error returned. If null, any changes will
be applied to the current state.

o emails: "Id[EmailImport]"

A map of creation id (client specified) to EmailImport objects.

An *EmailImport* object has the following properties:

o blobId: "Id"

The id of the blob containing the raw message [RFC5322].

o mailboxIds: "Id[Boolean]"

The ids of the Mailboxes to assign this Email to. At least one
Mailbox MUST be given.

o keywords: "String[Boolean]" (default: {})

The keywords to apply to the Email.

o receivedAt: "UTCDate" (default: time of most recent Received
header, or time of import on server if none)

The "receivedAt" date to set on the Email.

Each Email to import is considered an atomic unit that may succeed or
fail individually. Importing successfully creates a new Email object
from the data referenced by the blobId and applies the given
Mailboxes, keywords, and receivedAt date.

The server MAY forbid two Email objects with the same exact content
[RFC5322], or even just with the same Message-ID [RFC5322], to
coexist within an account. In this case, it MUST reject attempts to
import an Email considered to be a duplicate with an "alreadyExists"
SetError. An "existingId" property of type "Id" MUST be included on
the SetError object with the id of the existing Email. If duplicates
are allowed, the newly created Email object MUST have a separate id
and independent mutable properties to the existing object.

If the "blobId", "mailboxIds", or "keywords" properties are invalid
(e.g., missing, wrong type, id not found), the server MUST reject the
import with an "invalidProperties" SetError.

If the Email cannot be imported because it would take the account
over quota, the import should be rejected with an "overQuota"
SetError.

If the blob referenced is not a valid message [RFC5322], the server
MAY modify the message to fix errors (such as removing NUL octets or
fixing invalid headers). If it does this, the "blobId" on the
response MUST represent the new representation and therefore be
different to the "blobId" on the EmailImport object. Alternatively,
the server MAY reject the import with an "invalidEmail" SetError.

The response has the following arguments:

o accountId: "Id"

The id of the account used for this call.

o oldState: "String|null"

The state string that would have been returned by "Email/get" on
this account before making the requested changes, or null if the
server doesn't know what the previous state string was.

o newState: "String"

The state string that will now be returned by "Email/get" on this
account.

o created: "Id[Email]|null"
A map of the creation id to an object containing the "id",
"blobId", "threadId", and "size" properties for each successfully
imported Email, or null if none.

o notCreated: "Id[SetError]|null"

A map of the creation id to a SetError object for each Email that
failed to be created, or null if all successful. The possible
errors are defined above.

The following additional errors may be returned instead of the
"Email/import" response:

"stateMismatch": An "ifInState" argument was supplied, and it does
not match the current state.

4.9. Email/parse

This method allows you to parse blobs as messages [RFC5322] to get
Email objects. The server MUST support messages with EAI headers
[RFC6532]. This can be used to parse and display attached messages
without having to import them as top-level Email objects in the mail
store in their own right.

The following metadata properties on the Email objects will be null
if requested:

o id

o mailboxIds

o keywords

o receivedAt

The "threadId" property of the Email MAY be present if the server can
calculate which Thread the Email would be assigned to were it to be
imported. Otherwise, this too is null if fetched.

The "Email/parse" method takes the following arguments:

o accountId: "Id"

The id of the account to use.

o blobIds: "Id[]"

The ids of the blobs to parse.

o properties: "String[]"

If supplied, only the properties listed in the array are returned
for each Email object. If omitted, defaults to:

[ "messageId", "inReplyTo", "references", "sender", "from", "to",
"cc", "bcc", "replyTo", "subject", "sentAt", "hasAttachment",
"preview", "bodyValues", "textBody", "htmlBody", "attachments" ]

o bodyProperties: "String[]"

A list of properties to fetch for each EmailBodyPart returned. If
omitted, defaults to the same value as the "Email/get"
"bodyProperties" default argument.

o fetchTextBodyValues: "Boolean" (default: false)

If true, the "bodyValues" property includes any "text/*" part in
the "textBody" property.

o fetchHTMLBodyValues: "Boolean" (default: false)

If true, the "bodyValues" property includes any "text/*" part in
the "htmlBody" property.

o fetchAllBodyValues: "Boolean" (default: false)

If true, the "bodyValues" property includes any "text/*" part in
the "bodyStructure" property.

o maxBodyValueBytes: "UnsignedInt" (default: 0)

The response has the following arguments:

o accountId: "Id"
The id of the account used for the call.

o parsed: "Id[Email]|null"

A map of blob id to parsed Email representation for each
successfully parsed blob, or null if none.

o notParsable: "Id[]|null"

A list of ids given that corresponded to blobs that could not be
parsed as Emails, or null if none.

o notFound: "Id[]|null"

A list of blob ids given that could not be found, or null if none.

Where a specific header field is requested as a property, the
capitalization of the property name in the response MUST be identical
to that used in the request.

4.10. Examples

A client logs in for the first time. It first fetches the set of
Mailboxes. Now it will display the inbox to the user, which we will
presume has Mailbox id "fb666a55". The inbox may be (very!) large,
but the user's screen is only so big, so the client can just load the
Threads it needs to fill the screen and then load in more only when
the user scrolls. The client sends this request:

[[ "Email/query",{
"accountId": "ue150411c",
"filter": {
"inMailbox": "fb666a55"
},
"sort": [{
"isAscending": false,
"property": "receivedAt"
}],
"collapseThreads": true,
"position": 0,
"limit": 30,
"calculateTotal": true
}, "0" ],
[ "Email/get", {
"accountId": "ue150411c",
"#ids": {
"resultOf": "0",
"name": "Email/query",
"path": "/ids"
},
"properties": [
"threadId"
]
}, "1" ],
[ "Thread/get", {
"accountId": "ue150411c",
"#ids": {
"resultOf": "1",
"name": "Email/get",
"path": "/list/*/threadId"
}
}, "2" ],
[ "Email/get", {
"accountId": "ue150411c",
"#ids": {
"resultOf": "2",
"name": "Thread/get",
"path": "/list/*/emailIds"
},
"properties": [
"threadId",
"mailboxIds",
"keywords",
"hasAttachment",
"from",
"subject",
"receivedAt",
"size",
"preview"
]
}, "3" ]]

Let's break down the 4 method calls to see what they're doing:

"0": This asks the server for the ids of the first 30 Email objects
in the inbox, sorted newest first, ignoring Emails from the same
Thread as a newer Email in the Mailbox (i.e., it is the first 30
unique Threads).

"1": Now we use a back-reference to fetch the Thread ids for each of
these Email ids.

"2": Another back-reference fetches the Thread object for each of
these Thread ids.

"3": Finally, we fetch the information we need to display the Mailbox
listing (but no more!) for every Email in each of these 30 Threads.
The client may aggregate this data for display, for example, by
showing the Thread as "flagged" if any of the Emails in it has the
"$flagged" keyword.

The response from the server may look something like this:

[[ "Email/query", {
"accountId": "ue150411c",
"queryState": "09aa9a075588-780599:0",
"canCalculateChanges": true,
"position": 0,
"total": 115,
"ids": [ "Ma783e5cdf5f2deffbc97930a",
"M9bd17497e2a99cb345fc1d0a", ... ]
}, "0" ],
[ "Email/get", {
"accountId": "ue150411c",
"state": "780599",
"list": [{
"id": "Ma783e5cdf5f2deffbc97930a",
"threadId": "T36703c2cfe9bd5ed"
}, {
"id": "M9bd17497e2a99cb345fc1d0a",
"threadId": "T0a22ad76e9c097a1"
}, ... ],
"notFound": []
}, "1" ],
[ "Thread/get", {
"accountId": "ue150411c",
"state": "22a8728b",
"list": [{
"id": "T36703c2cfe9bd5ed",
"emailIds": [ "Ma783e5cdf5f2deffbc97930a" ]
}, {
"id": "T0a22ad76e9c097a1",
"emailIds": [ "M3b568670a63e5d100f518fa5",
"M9bd17497e2a99cb345fc1d0a" ]
}, ... ],
"notFound": []
}, "2" ],
[ "Email/get", {
"accountId": "ue150411c",
"state": "780599",
"list": [{
"id": "Ma783e5cdf5f2deffbc97930a",
"threadId": "T36703c2cfe9bd5ed",
"mailboxIds": {
"fb666a55": true
},
"keywords": {
"$seen": true,
"$flagged": true
},
"hasAttachment": true,
"from": [{
"email": "jdoe@example.com",
"name": "Jane Doe"
}],
"subject": "The Big Reveal",
"receivedAt": "2018-06-27T00:20:35Z",
"size": 175047,
"preview": "As you may be aware, we are required to prepare a
presentation where we wow a panel of 5 random members of the
public, on or before 30 June each year. We have drafted..."
},
...
],
"notFound": []
}, "3" ]]

Now, on another device, the user marks the first Email as unread,
sending this API request:

[[ "Email/set", {
"accountId": "ue150411c",
"update": {
"Ma783e5cdf5f2deffbc97930a": {
"keywords/$seen": null
}
}
}, "0" ]]

The server applies this and sends the success response:

[[ "Email/set", {
"accountId": "ue150411c",
"oldState": "780605",
"newState": "780606",
"updated": {
"Ma783e5cdf5f2deffbc97930a": null
},
...
}, "0" ]]

The user also deletes a few Emails, and then a new message arrives.

Back on our original machine, we receive a push update that the state
string for Email is now "780800". As this does not match the
client's current state, it issues a request for the changes:

[[ "Email/changes", {
"accountId": "ue150411c",
"sinceState": "780605",
"maxChanges": 50
}, "3" ],
[ "Email/queryChanges", {
"accountId": "ue150411c",
"filter": {
"inMailbox": "fb666a55"
},
"sort": [{
"property": "receivedAt",
"isAscending": false
}],
"collapseThreads": true,
"sinceQueryState": "09aa9a075588-780599:0",
"upToId": "Mc2781d5e856a908d8a35a564",
"maxChanges": 25,
"calculateTotal": true
}, "11" ]]

The response:

[[ "Email/changes", {
"accountId": "ue150411c",
"oldState": "780605",
"newState": "780800",
"hasMoreChanges": false,
"created": [ "Me8de6c9f6de198239b982ea2" ],
"updated": [ "Ma783e5cdf5f2deffbc97930a" ],
"destroyed": [ "M9bd17497e2a99cb345fc1d0a", ... ]
}, "3" ],
[ "Email/queryChanges", {
"accountId": "ue150411c",
"oldQueryState": "09aa9a075588-780599:0",
"newQueryState": "e35e9facf117-780615:0",
"added": [{
"id": "Me8de6c9f6de198239b982ea2",
"index": 0
}],
"removed": [ "M9bd17497e2a99cb345fc1d0a" ],
"total": 115
}, "11" ]]

The client can update its local cache of the query results by
removing "M9bd17497e2a99cb345fc1d0a" and then splicing in
"Me8de6c9f6de198239b982ea2" at position 0. As it does not have the
data for this new Email, it will then fetch it (it also could have
done this in the same request using back-references).

It knows something has changed about "Ma783e5cdf5f2deffbc97930a", so
it will refetch the Mailbox ids and keywords (the only mutable
properties) for this Email too.

The user starts composing a new Email. The email is plaintext and
the client knows the email in in English so adds this metadata to the
body part. The user saves a draft while the composition is still in
progress. The client sends:

[[ "Email/set", {
"accountId": "ue150411c",
"create": {
"k192": {
"mailboxIds": {
"2ea1ca41b38e": true
},
"keywords": {
"$seen": true,
"$draft": true
},
"from": [{
"name": "Joe Bloggs",
"email": "joe@example.com"
}],
"subject": "World domination",
"receivedAt": "2018-07-10T01:03:11Z",
"sentAt": "2018-07-10T11:03:11+10:00",
"bodyStructure": {
"type": "text/plain",
"partId": "bd48",
"header:Content-Language": "en"
},
"bodyValues": {
"bd48": {
"value": "I have the most brilliant plan. Let me tell
you all about it. What we do is, we",
"isTruncated": false
}
}
}
}
}, "0" ]]

The server creates the message and sends the success response:

[[ "Email/set", {
"accountId": "ue150411c",
"oldState": "780823",
"newState": "780839",
"created": {
"k192": {
"id": "Mf40b5f831efa7233b9eb1c7f",
"blobId": "Gf40b5f831efa7233b9eb1c7f8f97d84eeeee64f7",
"threadId": "Td957e72e89f516dc",
"size": 359
}
},
...
}, "0" ]]

The message created on the server looks something like this:

Message-Id: <bbce0ae9-58be-4b24-ac82-deb840d58016@sloti7d1t02>
User-Agent: Cyrus-JMAP/3.1.6-736-gdfb8e44
Mime-Version: 1.0
Date: Tue, 10 Jul 2018 11:03:11 +1000
From: "Joe Bloggs" <joe@example.com>
Subject: World domination
Content-Language: en
Content-Type: text/plain

I have the most brilliant plan. Let me tell you all about it. What we
do is, we

The user adds a recipient and converts the message to HTML so they
can add formatting, then saves an updated draft:

[[ "Email/set", {
"accountId": "ue150411c",
"create": {
"k1546": {
"mailboxIds": {
"2ea1ca41b38e": true
},
"keywords": {
"$seen": true,
"$draft": true
},
"from": [{
"name": "Joe Bloggs",
"email": "joe@example.com"
}],
"to": [{
"name": "John",
"email": "john@example.com"
}],
"subject": "World domination",
"receivedAt": "2018-07-10T01:05:08Z",
"sentAt": "2018-07-10T11:05:08+10:00",
"bodyStructure": {
"type": "multipart/alternative",
"subParts": [{
"partId": "a49d",
"type": "text/html",
"header:Content-Language": "en"
}, {
"partId": "bd48",
"type": "text/plain",
"header:Content-Language": "en"
}]
},
"bodyValues": {
"bd48": {
"value": "I have the most brilliant plan. Let me tell
you all about it. What we do is, we",
"isTruncated": false
},
"a49d": {
"value": "<!DOCTYPE html><html><head><title></title>
<style type=\"text/css\">div{font-size:16px}</style></head>
<body><div>I have the most <b>brilliant</b> plan. Let me
tell you all about it. What we do is, we</div></body></html>", we</div></body>
</html>",
"isTruncated": false
}
}
}
},
"destroy": [ "Mf40b5f831efa7233b9eb1c7f" ]
}, "0" ]]

The server creates the new draft, deletes the old one, and sends the
success response:

[[ "Email/set", {
"accountId": "ue150411c",
"oldState": "780839",
"newState": "780842",
"created": {
"k1546": {
"id": "Md45b47b4877521042cec0938",
"blobId": "Ge8de6c9f6de198239b982ea214e0f3a704e4af74",
"threadId": "Td957e72e89f516dc",
"size": 11721
}
},
"destroyed": [ "Mf40b5f831efa7233b9eb1c7f" ],
...
}, "0" ]]

The client moves this draft to a different account. The only way to
do this is via the "Email/copy" method. It MUST set a new
"mailboxIds" property, since the current value will not be valid
Mailbox ids in the destination account:

[[ "Email/copy", {
"fromAccountId": "ue150411c",
"accountId": "u6c6c41ac",
"create": {
"k45": {
"id": "Md45b47b4877521042cec0938",
"mailboxIds": {
"75a4c956": true
}
}
},
"onSuccessDestroyOriginal": true
}, "0" ]]

The server successfully copies the Email and deletes the original.
Due to the implicit call to "Email/set", there are two responses to
the single method call, both with the same method call id:

[[ "Email/copy", {
"fromAccountId": "ue150411c",
"accountId": "u6c6c41ac",
"oldState": "7ee7e9263a6d",
"newState": "5a0d2447ed26",
"created": {
"k45": {
"id": "M138f9954a5cd2423daeafa55",
"blobId": "G6b9fb047cba722c48c611e79233d057c6b0b74e8",
"threadId": "T2f242ea424a4079a",
"size": 11721
}
},
"notCreated": null
}, "0" ],
[ "Email/set", {
"accountId": "ue150411c",
"oldState": "780842",
"newState": "780871",
"destroyed": [ "Md45b47b4877521042cec0938" ],
...
}, "0" ]]

5. Search Snippets

When doing a search on a "String" property, the client may wish to
show the relevant section of the body that matches the search as a
preview and to highlight any matching terms in both this and the
subject of the Email. Search snippets represent this data.

A *SearchSnippet* object has the following properties:

o emailId: "Id"

The Email id the snippet applies to.

o subject: "String|null"

If text from the filter matches the subject, this is the subject
of the Email with the following transformations:

1. Any instance of the following three characters MUST be
replaced by an appropriate HTML entity: & (ampersand), <
(less-than sign), and > (greater-than sign) [HTML]. Other
characters MAY also be replaced with an HTML entity form.

2. The matching words/phrases from the filter are wrapped in HTML
"<mark></mark>" tags.

If the subject does not match text from the filter, this property
is null.

o preview: "String|null"

If text from the filter matches the plaintext or HTML body, this
is the relevant section of the body (converted to plaintext if
originally HTML), with the same transformations as the "subject"
property. It MUST NOT be bigger than 255 octets in size. If the
body does not contain a match for the text from the filter, this
property is null.

What is a relevant section of the body for preview is server defined.
If the server is unable to determine search snippets, it MUST return
null for both the "subject" and "preview" properties.

Note that unlike most data types, a SearchSnippet DOES NOT have a
property called "id".

The following JMAP method is supported.

5.1. SearchSnippet/get

To fetch search snippets, make a call to "SearchSnippet/get". It
takes the following arguments:

o accountId: "Id"

The id of the account to use.

o filter: "FilterOperator|FilterCondition|null"

The same filter as passed to "Email/query"; see the description of
this method in Section 4.4 for details.

o emailIds: "Id[]"

The ids of the Emails to fetch snippets for.

The response has the following arguments:

o accountId: "Id"

The id of the account used for the call.

o list: "SearchSnippet[]"
An array of SearchSnippet objects for the requested Email ids.
This may not be in the same order as the ids that were in the
request.

o notFound: "Id[]|null"

An array of Email ids requested that could not be found, or null
if all ids were found.

As the search snippets are derived from the message content and the
algorithm for doing so could change over time, fetching the same
snippets a second time MAY return a different result. However, the
previous value is not considered incorrect, so there is no state
string or update mechanism needed.

The following additional errors may be returned instead of the
"SearchSnippet/get" response:

"requestTooLarge": The number of "emailIds" requested by the client
exceeds the maximum number the server is willing to process in a
single method call.

"unsupportedFilter": The server is unable to process the given
"filter" for any reason.

5.2. Example

Here, we did an "Email/query" to search for any Email in the account
containing the word "foo"; now, we are fetching the search snippets
for some of the ids that were returned in the results:

[[ "SearchSnippet/get", {
"accountId": "ue150411c",
"filter": {
"text": "foo"
},
"emailIds": [
"M44200ec123de277c0c1ce69c",
"M7bcbcb0b58d7729686e83d99",
"M28d12783a0969584b6deaac0",
...
]
}, "0" ]]

Example response:

[[ "SearchSnippet/get", {
"accountId": "ue150411c",
"list": [{
"emailId": "M44200ec123de277c0c1ce69c",
"subject": null,
"preview": null
}, {
"emailId": "M7bcbcb0b58d7729686e83d99",
"subject": "The <mark>Foo</mark>sball competition",
"preview": "...year the <mark>foo</mark>sball competition will
be held in the Stadium de ..."
}, {
"emailId": "M28d12783a0969584b6deaac0",
"subject": null,
"preview": "...the <mark>Foo</mark>/bar method results often
returns &lt;1 widget rather than the complete..."
},
...
],
"notFound": null
}, "0" ]]

6. Identities

An *Identity* object stores information about an email address or
domain the user may send from. It has the following properties:

o id: "Id" (immutable; server-set)

The id of the Identity.

o name: "String" (default: "")

The "From" name the client SHOULD use when creating a new Email
from this Identity.

o email: "String" (immutable)

The "From" email address the client MUST use when creating a new
Email from this Identity. If the "mailbox" part of the address
(the section before the "@") is the single character "*" (e.g.,
"*@example.com"), the client may use any valid address ending in
that domain (e.g., "foo@example.com").

o replyTo: "EmailAddress[]|null" (default: null)

The Reply-To value the client SHOULD set when creating a new Email
from this Identity.

o bcc: "EmailAddress[]|null" (default: null)

The Bcc value the client SHOULD set when creating a new Email from
this Identity.

o textSignature: "String" (default: "")

A signature the client SHOULD insert into new plaintext messages
that will be sent from this Identity. Clients MAY ignore this
and/or combine this with a client-specific signature preference.

o htmlSignature: "String" (default: "")

A signature the client SHOULD insert into new HTML messages that
will be sent from this Identity. This text MUST be an HTML
snippet to be inserted into the "<body></body>" section of the
HTML. Clients MAY ignore this and/or combine this with a client-
specific signature preference.

o mayDelete: "Boolean" (server-set)

Is the user allowed to delete this Identity? Servers may wish to
set this to false for the user's username or other default
address. Attempts to destroy an Identity with "mayDelete: false"
will be rejected with a standard "forbidden" SetError.

See the "Addresses" header form description in the Email object
(Section 4.1.2.3) for the definition of EmailAddress.

Multiple identities with the same email address MAY exist, to allow
for different settings the user wants to pick between (for example,
with different names/signatures).

The following JMAP methods are supported.

6.1. Identity/get

Standard

This is a standard "/get" method as described in [RFC8620],
Section 5.1. The "ids" argument may be null to fetch all at once.

6.2. Identity/changes

Standard

This is a standard "/changes" method as described in [RFC8620],
Section 5.2.

6.3. Identity/set

Standard

This is a standard "/set" method as described in [RFC8620],
Section 5.3. The following extra SetError types are defined:

For "create":

o "forbiddenFrom": The user is not allowed to send from the address
given as the "email" property of the Identity.

6.4. Example

Request:

[ "Identity/get", {
"accountId": "acme"
}, "0" ]

with response:

[ "Identity/get", {
"accountId": "acme",
"state": "99401312ae-11-333",
"list": [
{
"id": "XD-3301-222-11_22AAz",
"name": "Joe Bloggs",
"email": "joe@example.com",
"replyTo": null,
"bcc": [{
"name": null,
"email": "joe+archive@example.com"
}],
"textSignature": "-- \nJoe Bloggs\nMaster of Email",
"htmlSignature": "<div><b>Joe Bloggs</b></div>
<div>Master of Email</div>",
"mayDelete": false
},
{
"id": "XD-9911312-11_22AAz",
"name": "Joe B",
"email": "*@example.com",
"replyTo": null,
"bcc": null,
"textSignature": "",
"htmlSignature": "",
"mayDelete": true
}
],
"notFound": []
}, "0" ]

7. Email Submission

An *EmailSubmission* object represents the submission of an Email for
delivery to one or more recipients. It has the following properties:

o id: "Id" (immutable; server-set)

The id of the EmailSubmission.

o identityId: "Id" (immutable)

The id of the Identity to associate with this submission.

o emailId: "Id" (immutable)
The id of the Email to send. The Email being sent does not have
to be a draft, for example, when "redirecting" an existing Email
to a different address.

o threadId: "Id" (immutable; server-set)

The Thread id of the Email to send. This is set by the server to
the "threadId" property of the Email referenced by the "emailId".

o envelope: "Envelope|null" (immutable)

Information for use when sending via SMTP. An *Envelope* object
has the following properties:

* mailFrom: "Address"

The email address to use as the return address in the SMTP
submission, plus any parameters to pass with the MAIL FROM
address. The JMAP server MAY allow the address to be the empty
string.

When a JMAP server performs an SMTP message submission, it MAY
use the same id string for the ENVID parameter [RFC3461] and
the EmailSubmission object id. Servers that do this MAY
replace a client-provided value for ENVID with a server-
provided value.

* rcptTo: "Address[]"

The email addresses to send the message to, and any RCPT TO
parameters to pass with the recipient.

An *Address* object has the following properties:

* email: "String"

The email address being represented by the object. This is a
"Mailbox" as used in the Reverse-path or Forward-path of the
MAIL FROM or RCPT TO command in [RFC5321].

* parameters: "Object|null"

Any parameters to send with the email address (either mail-
parameter or rcpt-parameter as appropriate, as specified in
[RFC5321]). If supplied, each key in the object is a parameter
name, and the value is either the parameter value (type
"String") or null if the parameter does not take a value. For
both name and value, any xtext or unitext encodings are removed
(see [RFC3461] and [RFC6533]) and JSON string encoding is
applied.

If the "envelope" property is null or omitted on creation, the
server MUST generate this from the referenced Email as follows:

* "mailFrom": The email address in the Sender header field, if
present; otherwise, it's the email address in the From header
field, if present. In either case, no parameters are added.

If multiple addresses are present in one of these header
fields, or there is more than one Sender/From header field, the
server SHOULD reject the EmailSubmission as invalid; otherwise,
it MUST take the first address in the last Sender/From header
field.

If the address found from this is not allowed by the Identity
associated with this submission, the "email" property from the
Identity MUST be used instead.

* "rcptTo": The deduplicated set of email addresses from the To,
Cc, and Bcc header fields, if present, with no parameters for
any of them.

o sendAt: "UTCDate" (immutable; server-set)

The date the submission was/will be released for delivery. If the
client successfully used FUTURERELEASE [RFC4865] with the
submission, this MUST be the time when the server will release the
message; otherwise, it MUST be the time the EmailSubmission was
created.

o undoStatus: "String"

This represents whether the submission may be canceled. This is
server set on create and MUST be one of the following values:

* "pending": It may be possible to cancel this submission.

* "final": The message has been relayed to at least one recipient
in a manner that cannot be recalled. It is no longer possible
to cancel this submission.

* "canceled": The submission was canceled and will not be
delivered to any recipient.

On systems that do not support unsending, the value of this
property will always be "final". On systems that do support
canceling submission, it will start as "pending" and MAY
transition to "final" when the server knows it definitely cannot
recall the message, but it MAY just remain "pending". If in
pending state, a client can attempt to cancel the submission by
setting this property to "canceled"; if the update succeeds, the
submission was successfully canceled, and the message has not been
delivered to any of the original recipients.

o deliveryStatus: "String[DeliveryStatus]|null" (server-set)

This represents the delivery status for each of the submission's
recipients, if known. This property MAY not be supported by all
servers, in which case it will remain null. Servers that support
it SHOULD update the EmailSubmission object each time the status
of any of the recipients changes, even if some recipients are
still being retried.

This value is a map from the email address of each recipient to a
DeliveryStatus object.

A *DeliveryStatus* object has the following properties:

* smtpReply: "String"

The SMTP reply string returned for this recipient when the
server last tried to relay the message, or in a later Delivery
Status Notification (DSN, as defined in [RFC3464]) response for
the message. This SHOULD be the response to the RCPT TO stage,
unless this was accepted and the message as a whole was
rejected at the end of the DATA stage, in which case the DATA
stage reply SHOULD be used instead.

Multi-line SMTP responses should be concatenated to a single
string as follows:

+ The hyphen following the SMTP code on all but the last line
is replaced with a space.

+ Any prefix in common with the first line is stripped from
lines after the first.

+ CRLF is replaced by a space.

For example:

550-5.7.1 Our system has detected that this message is
550 5.7.1 likely spam.

would become:

550 5.7.1 Our system has detected that this message is likely spam.

For messages relayed via an alternative to SMTP, the server MAY
generate a synthetic string representing the status instead.
If it does this, the string MUST be of the following form:

+ A 3-digit SMTP reply code, as defined in [RFC5321],
Section 4.2.3.

+ Then a single space character.

+ Then an SMTP Enhanced Mail System Status Code as defined in
[RFC3463], with a registry defined in [RFC5248].

+ Then a single space character.

+ Then an implementation-specific information string with a
human-readable explanation of the response.

* delivered: "String"

Represents whether the message has been successfully delivered
to the recipient. This MUST be one of the following values:

+ "queued": The message is in a local mail queue and the
status will change once it exits the local mail queues. The
"smtpReply" property may still change.

+ "yes": The message was successfully delivered to the mail
store of the recipient. The "smtpReply" property is final.

+ "no": Delivery to the recipient permanently failed. The
"smtpReply" property is final.

+ "unknown": The final delivery status is unknown, (e.g., it
was relayed to an external machine and no further
information is available). The "smtpReply" property may
still change if a DSN arrives.

Note that successful relaying to an external SMTP server SHOULD
NOT be taken as an indication that the message has successfully
reached the final mail store. In this case though, the server
may receive a DSN response, if requested.

If a DSN is received for the recipient with Action equal to
"delivered", as per [RFC3464], Section 2.3.3, then the
"delivered" property SHOULD be set to "yes"; if the Action
equals "failed", the property SHOULD be set to "no". Receipt
of any other DSN SHOULD NOT affect this property.

The server MAY also set this property based on other feedback
channels.

* displayed: "String"

Represents whether the message has been displayed to the
recipient. This MUST be one of the following values:

+ "unknown": The display status is unknown. This is the
initial value.

+ "yes": The recipient's system claims the message content has
been displayed to the recipient. Note that there is no
guarantee that the recipient has noticed, read, or
understood the content.

If a Message Disposition Notification (MDN) is received for
this recipient with Disposition-Type (as per [RFC8098],
Section 3.2.6.2) equal to "displayed", this property SHOULD be
set to "yes".

The server MAY also set this property based on other feedback
channels.

o dsnBlobIds: "Id[]" (server-set)

A list of blob ids for DSNs [RFC3464] received for this
submission, in order of receipt, oldest first. The blob is the
whole MIME message (with a top-level content-type of "multipart/
report"), as received.

o mdnBlobIds: "Id[]" (server-set)

A list of blob ids for MDNs [RFC8098] received for this
submission, in order of receipt, oldest first. The blob is the
whole MIME message (with a top-level content-type of "multipart/
report"), as received.

JMAP servers MAY choose not to expose DSN and MDN responses as Email
objects if they correlate to an EmailSubmission object. It SHOULD
only do this if it exposes them in the "dsnBlobIds" and "mdnblobIds"
fields instead, and it expects the user to be using clients capable
of fetching and displaying delivery status via the EmailSubmission
object.

For efficiency, a server MAY destroy EmailSubmission objects at any
time after the message is successfully sent or after it has finished
retrying to send the message. For very basic SMTP proxies, this MAY
be immediately after creation, as it has no way to assign a real id
and return the information again if fetched later.

The following JMAP methods are supported.

7.1. EmailSubmission/get

Standard

This is a standard "/get" method as described in [RFC8620],
Section 5.1.

7.2. EmailSubmission/changes

Standard

This is a standard "/changes" method as described in [RFC8620],
Section 5.2.

7.3. EmailSubmission/query

Standard

This is a standard "/query" method as described in [RFC8620],
Section 5.5.

A *FilterCondition* object has the following properties, any of which
may be omitted:

o identityIds: "Id[]"

The EmailSubmission "identityId" property must be in this list to
match the condition.

o emailIds: "Id[]"

The EmailSubmission "emailId" property must be in this list to
match the condition.

o threadIds: "Id[]"

The EmailSubmission "threadId" property must be in this list to
match the condition.

o undoStatus: "String"

The EmailSubmission "undoStatus" property must be identical to the
value given to match the condition.

o before: "UTCDate"
The "sendAt" property of the EmailSubmission object must be before
this date-time to match the condition.

o after: "UTCDate"

The "sendAt" property of the EmailSubmission object must be the
same as or after this date-time to match the condition.

An EmailSubmission object matches the FilterCondition if and only if
all of the given conditions match. If zero properties are specified,
it is automatically true for all objects.

The following EmailSubmission properties MUST be supported for
sorting:

o "emailId"

o "threadId"

o "sentAt"

7.4. EmailSubmission/queryChanges

Standard

This is a standard "/queryChanges" method as described in [RFC8620],
Section 5.6.

7.5. EmailSubmission/set

Standard

This is a standard "/set" method as described in [RFC8620],
Section 5.3 with the following two additional request arguments:

o onSuccessUpdateEmail: "Id[PatchObject]|null"

A map of EmailSubmission id to an object containing properties to
update on the Email object referenced by the EmailSubmission if
the create/update/destroy succeeds. (For references to
EmailSubmissions created in the same "/set" invocation, this is
equivalent to a creation-reference, so the id will be the creation
id prefixed with a "#".)

o onSuccessDestroyEmail: "Id[]|null"

A list of EmailSubmission ids for which the Email with the
corresponding "emailId" should be destroyed if the create/update/
destroy succeeds. (For references to EmailSubmission creations,
this is equivalent to a creation-reference, so the id will be the
creation id prefixed with a "#".)
After all create/update/destroy items in the "EmailSubmission/set"
invocation have been processed, a single implicit "Email/set" call
MUST be made to perform any changes requested in these two arguments.
The response to this MUST be returned after the "EmailSubmission/set"
response.

An Email is sent by creating an EmailSubmission object. When
processing each create, the server must check that the message is
valid, and the user has sufficient authorisation to send it. If the
creation succeeds, the message will be sent to the recipients given
in the envelope "rcptTo" parameter. The server MUST remove any Bcc
header field present on the message during delivery. The server MAY
add or remove other header fields from the submitted message or make
further alterations in accordance with the server's policy during
delivery.

If the referenced Email is destroyed at any point after the
EmailSubmission object is created, this MUST NOT change the behaviour
of the submission (i.e., it does not cancel a future send). The
"emailId" and "threadId" properties of the EmailSubmission object
remain, but trying to fetch them (with a standard "Email/get" call)
will return a "notFound" error if the corresponding objects have been
destroyed.

Similarly, destroying an EmailSubmission object MUST NOT affect the
deliveries it represents. It purely removes the record of the
submission. The server MAY automatically destroy EmailSubmission
objects after some time or in response to other triggers, and MAY
forbid the client from manually destroying EmailSubmission objects.

If the message to be sent is larger than the server supports sending,
a standard "tooLarge" SetError MUST be returned. A "maxSize"
"UnsignedInt" property MUST be present on the SetError specifying the
maximum size of an message that may be sent, in octets.

If the Email or Identity id given cannot be found, the submission
creation is rejected with a standard "invalidProperties" SetError.

The following extra SetError types are defined:

For "create":

o "invalidEmail" - The Email to be sent is invalid in some way. The
SetError SHOULD contain a property called "properties" of type
"String[]" that lists *all* the properties of the Email that were
invalid.

o "tooManyRecipients" - The envelope (supplied or generated) has
more recipients than the server allows. A "maxRecipients"
"UnsignedInt" property MUST also be present on the SetError
specifying the maximum number of allowed recipients.

o "noRecipients" - The envelope (supplied or generated) does not
have any rcptTo email addresses.

o "invalidRecipients" - The "rcptTo" property of the envelope
(supplied or generated) contains at least one rcptTo value, which
is not a valid email address for sending to. An
"invalidRecipients" "String[]" property MUST also be present on
the SetError, which is a list of the invalid addresses.

o "forbiddenMailFrom" - The server does not permit the user to send
a message with the envelope From address [RFC5321].

o "forbiddenFrom" - The server does not permit the user to send a
message with the From header field [RFC5322] of the message to be
sent.

o "forbiddenToSend" - The user does not have permission to send at
all right now for some reason. A "description" "String" property
MAY be present on the SetError object to display to the user why
they are not permitted.

For "update":

o "cannotUnsend" - The client attempted to update the "undoStatus"
of a valid EmailSubmission object from "pending" to "canceled",
but the message cannot be unsent.

7.5.1. Example

The following example presumes a draft of the Email to be sent has
already been saved, and its Email id is "M7f6ed5bcfd7e2604d1753f6c".
This call then sends the Email immediately, and if successful,
removes the "$draft" flag and moves it from the drafts folder (which
has Mailbox id "7cb4e8ee-df87-4757-b9c4-2ea1ca41b38e") to the sent
folder (which we presume has Mailbox id "73dbcb4b-bffc-48bd-8c2a-
a2e91ca672f6").

[[ "EmailSubmission/set", {
"accountId": "ue411d190",
"create": {
"k1490": {
"identityId": "I64588216",
"emailId": "M7f6ed5bcfd7e2604d1753f6c",
"envelope": {
"mailFrom": {
"email": "john@example.com",
"parameters": null
},
"rcptTo": [{
"email": "jane@example.com",
"parameters": null
},
...
]
}
}
},
"onSuccessUpdateEmail": {
"#k1490": {
"mailboxIds/7cb4e8ee-df87-4757-b9c4-2ea1ca41b38e": null,
"mailboxIds/73dbcb4b-bffc-48bd-8c2a-a2e91ca672f6": true,
"keywords/$draft": null
}
}
}, "0" ]]

A successful response might look like this. Note that there are two
responses due to the implicit "Email/set" call, but both have the
same method call id as they are due to the same call in the request:

[[ "EmailSubmission/set", {
"accountId": "ue411d190",
"oldState": "012421s6-8nrq-4ps4-n0p4-9330r951ns21",
"newState": "355421f6-8aed-4cf4-a0c4-7377e951af36",
"created": {
"k1490": {
"id": "ES-3bab7f9a-623e-4acf-99a5-2e67facb02a0"
}
}
}, "0" ],
[ "Email/set", {
"accountId": "ue411d190",
"oldState": "778193",
"newState": "778197",
"updated": {
"M7f6ed5bcfd7e2604d1753f6c": null
}
}, "0" ]]

Suppose instead an admin has removed sending rights for the user, so
the submission is rejected with a "forbiddenToSend" error. The
description argument of the error is intended for display to the
user, so it should be localised appropriately. Let's suppose the
request was sent with an Accept-Language header like this:

Accept-Language: de;q=0.9,en;q=0.8

The server should attempt to choose the best localisation from those
it has available based on the Accept-Language header, as described in
[RFC8620], Section 3.8. If the server has English, French, and
German translations, it would choose German as the preferred language
and return a response like this:

[[ "EmailSubmission/set", {
"accountId": "ue411d190",
"oldState": "012421s6-8nrq-4ps4-n0p4-9330r951ns21",
"newState": "012421s6-8nrq-4ps4-n0p4-9330r951ns21",
"notCreated": {
"k1490": {
"type": "forbiddenToSend",
"description": "Verzeihung, wegen verdaechtiger Aktivitaeten Ihres
Benutzerkontos haben wir den Versand von Nachrichten gesperrt.
Bitte wenden Sie sich fuer Hilfe an unser Support Team."
}
}
}, "0" ]]

8. Vacation Response

A vacation response sends an automatic reply when a message is
delivered to the mail store, informing the original sender that their
message may not be read for some time.

Automated message sending can produce undesirable behaviour. To
avoid this, implementors MUST follow the recommendations set forth in
[RFC3834].

The *VacationResponse* object represents the state of vacation-
response-related settings for an account. It has the following
properties:

o id: "Id" (immutable; server-set)

The id of the object. There is only ever one VacationResponse
object, and its id is "singleton".

o isEnabled: "Boolean"

Should a vacation response be sent if a message arrives between
the "fromDate" and "toDate"?

o fromDate: "UTCDate|null"

If "isEnabled" is true, messages that arrive on or after this
date-time (but before the "toDate" if defined) should receive the
user's vacation response. If null, the vacation response is
effective immediately.

o toDate: "UTCDate|null"

If "isEnabled" is true, messages that arrive before this date-time
(but on or after the "fromDate" if defined) should receive the
user's vacation response. If null, the vacation response is
effective indefinitely.

o subject: "String|null"

The subject that will be used by the message sent in response to
messages when the vacation response is enabled. If null, an
appropriate subject SHOULD be set by the server.

o textBody: "String|null"

The plaintext body to send in response to messages when the
vacation response is enabled. If this is null, the server SHOULD
generate a plaintext body part from the "htmlBody" when sending
vacation responses but MAY choose to send the response as HTML
only. If both "textBody" and "htmlBody" are null, an appropriate
default body SHOULD be generated for responses by the server.

o htmlBody: "String|null"

The HTML body to send in response to messages when the vacation
response is enabled. If this is null, the server MAY choose to
generate an HTML body part from the "textBody" when sending
vacation responses or MAY choose to send the response as plaintext
only.

The following JMAP methods are supported.

8.1. VacationResponse/get

Standard

This is a standard "/get" method as described in [RFC8620],
Section 5.1.

There MUST only be exactly one VacationResponse object in an account.
It MUST have the id "singleton".

8.2. VacationResponse/set

Standard

This is a standard "/set" method as described in [RFC8620],
Section 5.3.

9. Security Considerations

All security considerations of JMAP [RFC8620] apply to this
specification. Additional considerations specific to the data types
and functionality introduced by this document are described in the
following subsections.

9.1. EmailBodyPart Value

Service providers typically perform security filtering on incoming
messages, and it's important that the detection of content-type and
charset for the security filter aligns with the heuristics performed
by JMAP servers. Servers that apply heuristics to determine the
content-type or charset for an EmailBodyValue SHOULD document the
heuristics and provide a mechanism to turn them off in the event they
are misaligned with the security filter used at a particular mail
host.

Automatic conversion of charsets that allow hidden channels for ASCII
text, such as UTF-7, have been problematic for security filters in
the past, so server implementations can mitigate this risk by having
such conversions off-by-default and/or separately configurable.

To allow the client to restrict the volume of data it can receive in
response to a request, a maximum length may be requested for the data
returned for a textual body part. However, truncating the data may
change the semantic meaning, for example, truncating a URL changes
its location. Servers that scan for links to malicious sites should
take care to either ensure truncation is not at a semantically
significant point or rescan the truncated value for malicious content
before returning it.

9.2. HTML Email Display

HTML message bodies provide richer formatting for messages but
present a number of security challenges, especially when embedded in
a webmail context in combination with interface HTML. Clients that
render HTML messages should carefully consider the potential risks,
including:

o Embedded JavaScript can rewrite the message to change its content
on subsequent opening, allowing users to be mislead. In webmail
systems, if run in the same origin as the interface, it can access
and exfiltrate all private data accessible to the user, including
all other messages and potentially contacts, calendar events,
settings, and credentials. It can also rewrite the interface to
undetectably phish passwords. A compromise is likely to be
persistent, not just for the duration of page load, due to
exfiltration of session credentials or installation of a service
worker that can intercept all subsequent network requests
(however, this would only be possible if blob downloads are also
available on the same origin, and the service worker script is
attached to the message).

o HTML documents may load content directly from the Internet rather
than just referencing attached resources. For example, you may
have an "<img>" tag with an external "src" attribute. This may
leak to the sender when a message is opened, as well as the IP
address of the recipient. Cookies may also be sent and set by the
server, allowing tracking between different messages and even
website visits and advertising profiles.

o In webmail systems, CSS can break the layout or create phishing
vulnerabilities. For example, the use of "position:fixed" can
allow a message to draw content outside of its normal bounds,
potentially clickjacking a real interface element.

o If in a webmail context and not inside a separate frame, any
styles defined in CSS rules will apply to interface elements as
well if the selector matches, allowing the interface to be
modified. Similarly, any interface styles that match elements in
the message will alter their appearance, potentially breaking the
layout of the message.

o The link text in HTML has no necessary correlation with the actual
target of the link, which can be used to make phishing attacks
more convincing.

o Links opened from a message or embedded external content may leak
private info in the Referer header sent by default in most
systems.

o Forms can be used to mimic login boxes, providing a potent
phishing vector if allowed to submit directly from the message
display.

There are a number of ways clients can mitigate these issues, and a
defence-in-depth approach that uses a combination of techniques will
provide the strongest security.

o HTML can be filtered before rendering, stripping potentially
malicious content. Sanitising HTML correctly is tricky, and
implementors are strongly recommended to use a well-tested library
with a carefully vetted whitelist-only approach. New features
with unexpected security characteristics may be added to HTML
rendering engines in the future; a blacklist approach is likely to
result in security issues.

Subtle differences in parsing of HTML can introduce security
flaws: to filter with 100% accuracy, you need to use the same
parser that the HTML rendering engine will use.

o Encapsulating the message in an "<iframe sandbox>", as defined in
[HTML], Section 4.7.6, can help mitigate a number of risks. This
will:

* Disable JavaScript.

* Disable form submission.

* Prevent drawing outside of its bounds or conflicts between
message CSS and interface CSS.

* Establish a unique anonymous origin, separate to the containing
origin.

o A strong Content Security Policy (see <https://www.w3.org/TR/
CSP3/>) can, among other things, block JavaScript and the loading
of external content should it manage to evade the filter.

o The leakage of information in the Referer header can be mitigated
with the use of a referrer policy (see <https://www.w3.org/TR/
referrer-policy/>).

o A "crossorigin=anonymous" attribute on tags that load remote
content can prevent cookies from being sent.

o If adding "target=_blank" to open links in new tabs, also add
"rel=noopener" to ensure the page that opens cannot change the URL
in the original tab to redirect the user to a phishing site.

As highly complex software components, HTML rendering engines
increase the attack surface of a client considerably, especially when
being used to process untrusted, potentially malicious content.
Serious bugs have been found in image decoders, JavaScript engines,
and HTML parsers in the past, which could lead to full system
compromise. Clients using an engine should ensure they get the
latest version and continue to incorporate any security patches
released by the vendor.

9.3. Multiple Part Display

Messages may consist of multiple parts to be displayed sequentially
as a body. Clients MUST render each part in isolation and MUST NOT
concatenate the raw text values to render. Doing so may change the
overall semantics of the message. If the client or server is
decrypting a Pretty Good Privacy (PGP) or S/MIME encrypted part,
concatenating with other parts may leak the decrypted text to an
attacker, as described in [EFAIL].

9.4. Email Submission

SMTP submission servers [RFC6409] use a number of mechanisms to
mitigate damage caused by compromised user accounts and end-user
systems including rate limiting, anti-virus/anti-spam milters (mail
filters), and other technologies. The technologies work better when
they have more information about the client connection. If JMAP
email submission is implemented as a proxy to an SMTP submission
server, it is useful to communicate this information from the JMAP
proxy to the submission server. The de facto XCLIENT extension to
SMTP [XCLIENT] can be used to do this, but use of an authenticated
channel is recommended to limit use of that extension to explicitly
authorised proxies.

JMAP servers that proxy to an SMTP submission server SHOULD allow use
of the submissions port [RFC8314]. Implementation of a mechanism
similar to SMTP XCLIENT is strongly encouraged. While Simple
Authentication and Security Layer (SASL) PLAIN over TLS [RFC4616] is
presently the mandatory-to-implement mechanism for interoperability
with SMTP submission servers [RFC4954], a JMAP submission proxy
SHOULD implement and prefer a stronger mechanism for this use case
such as TLS client certificate authentication with SASL EXTERNAL
([RFC4422], Appendix A) or Salted Challenge Response Authentication
Mechanism (SCRAM) [RFC7677].

In the event the JMAP server directly relays mail to SMTP servers in
other administrative domains, implementation of the de facto [milter]
protocol is strongly encouraged to integrate with third-party
products that address security issues including anti-virus/anti-spam,
reputation protection, compliance archiving, and data loss
prevention. Proxying to a local SMTP submission server may be a
simpler way to provide such security services.

9.5. Partial Account Access

A user may only have permission to access a subset of the data that
exists in an account. To avoid leaking unauthorised information, in
such a situation, the server MUST treat any data the user does not
have permission to access the same as if it did not exist.

For example, suppose user A has an account with two Mailboxes, inbox
and sent, but only shares the inbox with user B. In this case, when
user B fetches Mailboxes for this account, the server MUST behave as
though the sent Mailbox did not exist. Similarly, when querying or
fetching Email objects, it MUST treat any messages that just belong
to the sent Mailbox as though they did not exist. Fetching Thread
objects MUST only return ids for Email objects the user has
permission to access; if none, the Thread again MUST be treated the
same as if it did not exist.

If the server forbids a single account from having two identical
messages, or two messages with the same Message-Id header field, a
user with write access can use the error returned by trying to
create/import such a message to detect whether it already exists in
an inaccessible portion of the account.

9.6. Permission to Send from an Address

In recent years, the email ecosystem has moved towards associating
trust with the From address in the message [RFC5322], particularly
with schemes such as Domain-based Message Authentication, Reporting,
and Conformance (DMARC) [RFC7489].

The set of Identity objects (see Section 6) in an account lets the
client know which email addresses the user has permission to send
from. Each email submission is associated with an Identity, and
servers SHOULD reject submissions where the From header field of the
message does not correspond to the associated Identity.

The server MAY allow an exception to send an exact copy of an
existing message received into the mail store to another address
(otherwise known as "redirecting" or "bouncing"), although it is
RECOMMENDED the server limit this to destinations the user has
verified they also control.

If the user attempts to create a new Identity object, the server MUST
reject it with the appropriate error if the user does not have
permission to use that email address to send from.

The SMTP MAIL FROM address [RFC5321] is often confused with the From
message header field [RFC5322]. The user generally only ever sees
the address in the message header field, and this is the primary one
to enforce. However, the server MUST also enforce appropriate
restrictions on the MAIL FROM address [RFC5321] to stop the user from
flooding a third-party address with bounces and non-delivery notices.

The JMAP submission model provides separate errors for impermissible
addresses in either context.

10. IANA Considerations

10.1. JMAP Capability Registration for "mail"

IANA has registered the "mail" JMAP Capability as follows:

Capability Name: urn:ietf:params:jmap:mail

Specification document: this document

Intended use: common

Change Controller: IETF

Security and privacy considerations: this document, Section 9

10.2. JMAP Capability Registration for "submission"

IANA has registered the "submission" JMAP Capability as follows:

Capability Name: urn:ietf:params:jmap:submission
Specification document: this document

Intended use: common

Change Controller: IETF

Security and privacy considerations: this document, Section 9

10.3. JMAP Capability Registration for "vacationresponse"

IANA has registered the "vacationresponse" JMAP Capability as
follows:

Capability Name: urn:ietf:params:jmap:vacationresponse

Specification document: this document

Intended use: common

Change Controller: IETF

Security and privacy considerations: this document, Section 9

10.4. IMAP and JMAP Keywords Registry

This document makes two changes to the IMAP keywords registry as
defined in [RFC5788].

First, the name of the registry is changed to the "IMAP and JMAP
Keywords" registry.

Second, a scope column is added to the template and registry
indicating whether a keyword applies to "IMAP-only", "JMAP-only",
"both", or "reserved". All keywords already in the IMAP keyword
registry have been marked with a scope of "both". The "reserved"
status can be used to prevent future registration of a name that
would be confusing if registered. Registration of keywords with
scope "reserved" omit most fields in the registration template (see
registration of "$recent" below for an example); such registrations
are intended to be infrequent.

IMAP clients MAY silently ignore any keywords marked "JMAP-only" or
"reserved" in the event they appear in protocol. JMAP clients MAY
silently ignore any keywords marked "IMAP-only" or "reserved" in the
event they appear in protocol.

New "JMAP-only" keywords are registered in the following subsections.
These keywords correspond to IMAP system keywords and are thus not
appropriate for use in IMAP. These keywords cannot be subsequently
registered for use in IMAP except via standards action.

10.4.1. Registration of JMAP Keyword "$draft"

This registers the "JMAP-only" keyword "$draft" in the "IMAP and JMAP
Keywords" registry.

Keyword name: $draft

Scope: JMAP-only

Purpose (description): This is set when the user wants to treat the
message as a draft the user is composing. This is the JMAP
equivalent of the IMAP \Draft flag.

Private or Shared on a server: BOTH

Is it an advisory keyword or may it cause an automatic action:
Automatic. If the account has an IMAP mailbox marked with the
\Drafts special use attribute [RFC6154], setting this flag MAY cause
the message to appear in that mailbox automatically. Certain JMAP
computed values such as "unreadEmails" will change as a result of
changing this flag. In addition, mail clients will typically present
draft messages in a composer window rather than a viewer window.

When/by whom the keyword is set/cleared: This is typically set by a
JMAP client when referring to a draft message. One model for draft
Emails would result in clearing this flag in an "EmailSubmission/set"
operation with an "onSuccessUpdateEmail" argument. In a mail store
shared by JMAP and IMAP, this is also set and cleared as necessary so
it matches the IMAP \Draft flag.

Related keywords: None

Related IMAP/JMAP Capabilities: SPECIAL-USE [RFC6154]

Security Considerations: A server implementing this keyword as a
shared keyword may disclose that a user considers the message a draft
message. This information would be exposed to other users with read
permission for the Mailbox keywords.

Published specification: this document

Person & email address to contact for further information: JMAP
mailing list <jmap@ietf.org>

Intended usage: COMMON
Owner/Change controller: IESG

10.4.2. Registration of JMAP Keyword "$seen"

This registers the "JMAP-only" keyword "$seen" in the "IMAP and JMAP
Keywords" registry.

Keyword name: $seen

Scope: JMAP-only

Purpose (description): This is set when the user wants to treat the
message as read. This is the JMAP equivalent of the IMAP \Seen flag.

Private or Shared on a server: BOTH

Is it an advisory keyword or may it cause an automatic action:
Advisory. However, certain JMAP computed values such as
"unreadEmails" will change as a result of changing this flag.

When/by whom the keyword is set/cleared: This is set by a JMAP client
when it presents the message content to the user; clients often offer
an option to clear this flag. In a mail store shared by JMAP and
IMAP, this is also set and cleared as necessary so it matches the
IMAP \Seen flag.

Related keywords: None

Related IMAP/JMAP Capabilities: None

Security Considerations: A server implementing this keyword as a
shared keyword may disclose that a user considers the message to have
been read. This information would be exposed to other users with
read permission for the Mailbox keywords.

Published specification: this document

Person & email address to contact for further information: JMAP
mailing list <jmap@ietf.org>

Intended usage: COMMON

Owner/Change controller: IESG

10.4.3. Registration of JMAP Keyword "$flagged"

This registers the "JMAP-only" keyword "$flagged" in the "IMAP and
JMAP Keywords" registry.

Keyword name: $flagged

Scope: JMAP-only

Purpose (description): This is set when the user wants to treat the
message as flagged for urgent/special attention. This is the JMAP
equivalent of the IMAP \Flagged flag.

Private or Shared on a server: BOTH

Is it an advisory keyword or may it cause an automatic action:
Automatic. If the account has an IMAP mailbox marked with the
\Flagged special use attribute [RFC6154], setting this flag MAY cause
the message to appear in that mailbox automatically.

When/by whom the keyword is set/cleared: JMAP clients typically allow
a user to set/clear this flag as desired. In a mail store shared by
JMAP and IMAP, this is also set and cleared as necessary so it
matches the IMAP \Flagged flag.

Related keywords: None

Related IMAP/JMAP Capabilities: SPECIAL-USE [RFC6154]

Security Considerations: A server implementing this keyword as a
shared keyword may disclose that a user considers the message as
flagged for urgent/special attention. This information would be
exposed to other users with read permission for the Mailbox keywords.

Published specification: this document

Person & email address to contact for further information: JMAP
mailing list <jmap@ietf.org>

Intended usage: COMMON

Owner/Change controller: IESG

10.4.4. Registration of JMAP Keyword "$answered"

This registers the "JMAP-only" keyword "$answered" in the "IMAP and
JMAP Keywords" registry.

Keyword name: $answered

Scope: JMAP-only

Purpose (description): This is set when the message has been
answered.

Private or Shared on a server: BOTH

Is it an advisory keyword or may it cause an automatic action:
Advisory.

When/by whom the keyword is set/cleared: JMAP clients typically set
this when submitting a reply or answer to the message. It may be set
by the "EmailSubmission/set" operation with an "onSuccessUpdateEmail"
argument. In a mail store shared by JMAP and IMAP, this is also set
and cleared as necessary so it matches the IMAP \Answered flag.

Related keywords: None

Related IMAP/JMAP Capabilities: None

Security Considerations: A server implementing this keyword as a
shared keyword may disclose that a user has replied to a message.
This information would be exposed to other users with read permission
for the Mailbox keywords.

Published specification: this document

Person & email address to contact for further information: JMAP
mailing list <jmap@ietf.org>

Intended usage: COMMON

Owner/Change controller: IESG

10.4.5. Registration of "$recent" Keyword

This registers the keyword "$recent" in the "IMAP and JMAP Keywords"
registry.

Keyword name: $recent

Scope: reserved

Purpose (description): This keyword is not used to avoid confusion
with the IMAP \Recent system flag.

Published specification: this document

Person & email address to contact for further information: JMAP
mailing list <jmap@ietf.org>

Owner/Change controller: IESG

10.5. IMAP Mailbox Name Attributes Registry

10.5.1. Registration of "inbox" Role

This registers the "JMAP-only" "inbox" attribute in the "IMAP Mailbox
Name Attributes" registry, as established in [RFC8457].

Attribute Name: Inbox

Description: New mail is delivered here by default.

Reference: This document, Section 10.5.1

Usage Notes: JMAP only

10.6. JMAP Error Codes Registry

The following subsections register several new error codes in the
"JMAP Error Codes" registry, as defined in [RFC8620].

10.6.1. mailboxHasChild

JMAP Error Code: mailboxHasChild

Intended use: common

Change controller: IETF

Reference: This document, Section 2.5

Description: The Mailbox still has at least one child Mailbox. The
client MUST remove these before it can delete the parent Mailbox.

10.6.2. mailboxHasEmail

JMAP Error Code: mailboxHasEmail

Intended use: common

Change controller: IETF
Reference: This document, Section 2.5

Description: The Mailbox has at least one message assigned to it, and
the onDestroyRemoveEmails argument was false.

10.6.3. blobNotFound

JMAP Error Code: blobNotFound

Intended use: common

Change controller: IETF

Reference: This document, Section 4.6

Description: At least one blob id referenced in the object doesn't
exist.

10.6.4. tooManyKeywords

JMAP Error Code: tooManyKeywords

Intended use: common

Change controller: IETF

Reference: This document, Section 4.6

Description: The change to the Email's keywords would exceed a
server-defined maximum.

10.6.5. tooManyMailboxes

JMAP Error Code: tooManyMailboxes

Intended use: common

Change controller: IETF

Reference: This document, Section 4.6

Description: The change to the set of Mailboxes that this Email is in
would exceed a server-defined maximum.

10.6.6. invalidEmail

JMAP Error Code: invalidEmail

Intended use: common

Change controller: IETF

Reference: This document, Section 7.5

Description: The Email to be sent is invalid in some way.

10.6.7. tooManyRecipients

JMAP Error Code: tooManyRecipients

Intended use: common

Change controller: IETF

Reference: This document, Section 7.5

Description: The envelope [RFC5321] (supplied or generated) has more
recipients than the server allows.

10.6.8. noRecipients

JMAP Error Code: noRecipients

Intended use: common

Change controller: IETF

Reference: This document, Section 7.5

Description: The envelope [RFC5321] (supplied or generated) does not
have any rcptTo email addresses.

10.6.9. invalidRecipients

JMAP Error Code: invalidRecipients

Intended use: common

Change controller: IETF

Reference: This document, Section 7.5
Description: The rcptTo property of the envelope [RFC5321] (supplied
or generated) contains at least one rcptTo value that is not a valid
email address for sending to.

10.6.10. forbiddenMailFrom

JMAP Error Code: forbiddenMailFrom

Intended use: common

Change controller: IETF

Reference: This document, Section 7.5

Description: The server does not permit the user to send a message
with this envelope From address [RFC5321].

10.6.11. forbiddenFrom

JMAP Error Code: forbiddenFrom

Intended use: common

Change controller: IETF

Reference: This document, Sections 6.3 and 7.5

Description: The server does not permit the user to send a message
with the From header field [RFC5322] of the message to be sent.

10.6.12. forbiddenToSend

JMAP Error Code: forbiddenToSend

Intended use: common

Change controller: IETF

Reference: This document, Section 7.5

Description: The user does not have permission to send at all right
now.

11. References

11.1. Normative References

[HTML] Faulkner, S., Eicholz, A., Leithead, T., Danilo, A., and
S. Moon, "HTML 5.2", World Wide Web Consortium
Recommendation REC-html52-20171214, December 2017,
<https://www.w3.org/TR/html52/>.

[RFC1870] Klensin, J., Freed, N., and K. Moore, "SMTP Service
Extension for Message Size Declaration", STD 10, RFC 1870,
DOI 10.17487/RFC1870, November 1995,
<https://www.rfc-editor.org/info/rfc1870>.

[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
<https://www.rfc-editor.org/info/rfc2045>.

[RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
Part Three: Message Header Extensions for Non-ASCII Text",
RFC 2047, DOI 10.17487/RFC2047, November 1996,
<https://www.rfc-editor.org/info/rfc2047>.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.

[RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded
Word Extensions: Character Sets, Languages, and
Continuations", RFC 2231, DOI 10.17487/RFC2231, November
1997, <https://www.rfc-editor.org/info/rfc2231>.

[RFC2369] Neufeld, G. and J. Baer, "The Use of URLs as Meta-Syntax
for Core Mail List Commands and their Transport through
Message Header Fields", RFC 2369, DOI 10.17487/RFC2369,
July 1998, <https://www.rfc-editor.org/info/rfc2369>.

[RFC2392] Levinson, E., "Content-ID and Message-ID Uniform Resource
Locators", RFC 2392, DOI 10.17487/RFC2392, August 1998,
<https://www.rfc-editor.org/info/rfc2392>.

[RFC2557] Palme, J., Hopmann, A., and N. Shelness, "MIME
Encapsulation of Aggregate Documents, such as HTML
(MHTML)", RFC 2557, DOI 10.17487/RFC2557, March 1999,
<https://www.rfc-editor.org/info/rfc2557>.

[RFC2852] Newman, D., "Deliver By SMTP Service Extension", RFC 2852,
DOI 10.17487/RFC2852, June 2000,
<https://www.rfc-editor.org/info/rfc2852>.

[RFC3282] Alvestrand, H., "Content Language Headers", RFC 3282,
DOI 10.17487/RFC3282, May 2002,
<https://www.rfc-editor.org/info/rfc3282>.

[RFC3461] Moore, K., "Simple Mail Transfer Protocol (SMTP) Service
Extension for Delivery Status Notifications (DSNs)",
RFC 3461, DOI 10.17487/RFC3461, January 2003,
<https://www.rfc-editor.org/info/rfc3461>.

[RFC3463] Vaudreuil, G., "Enhanced Mail System Status Codes",
RFC 3463, DOI 10.17487/RFC3463, January 2003,
<https://www.rfc-editor.org/info/rfc3463>.

[RFC3464] Moore, K. and G. Vaudreuil, "An Extensible Message Format
for Delivery Status Notifications", RFC 3464,
DOI 10.17487/RFC3464, January 2003,
<https://www.rfc-editor.org/info/rfc3464>.

[RFC3834] Moore, K., "Recommendations for Automatic Responses to
Electronic Mail", RFC 3834, DOI 10.17487/RFC3834, August
2004, <https://www.rfc-editor.org/info/rfc3834>.

[RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension",
RFC 4314, DOI 10.17487/RFC4314, December 2005,
<https://www.rfc-editor.org/info/rfc4314>.

[RFC4422] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple
Authentication and Security Layer (SASL)", RFC 4422,
DOI 10.17487/RFC4422, June 2006,
<https://www.rfc-editor.org/info/rfc4422>.

[RFC4616] Zeilenga, K., Ed., "The PLAIN Simple Authentication and
Security Layer (SASL) Mechanism", RFC 4616,
DOI 10.17487/RFC4616, August 2006,
<https://www.rfc-editor.org/info/rfc4616>.

[RFC4865] White, G. and G. Vaudreuil, "SMTP Submission Service
Extension for Future Message Release", RFC 4865,
DOI 10.17487/RFC4865, May 2007,
<https://www.rfc-editor.org/info/rfc4865>.

[RFC4954] Siemborski, R., Ed. and A. Melnikov, Ed., "SMTP Service
Extension for Authentication", RFC 4954,
DOI 10.17487/RFC4954, July 2007,
<https://www.rfc-editor.org/info/rfc4954>.

[RFC5198] Klensin, J. and M. Padlipsky, "Unicode Format for Network
Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008,
<https://www.rfc-editor.org/info/rfc5198>.

[RFC5248] Hansen, T. and J. Klensin, "A Registry for SMTP Enhanced
Mail System Status Codes", BCP 138, RFC 5248,
DOI 10.17487/RFC5248, June 2008,
<https://www.rfc-editor.org/info/rfc5248>.

[RFC5256] Crispin, M. and K. Murchison, "Internet Message Access
Protocol - SORT and THREAD Extensions", RFC 5256,
DOI 10.17487/RFC5256, June 2008,
<https://www.rfc-editor.org/info/rfc5256>.

[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
DOI 10.17487/RFC5321, October 2008,
<https://www.rfc-editor.org/info/rfc5321>.

[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
DOI 10.17487/RFC5322, October 2008,
<https://www.rfc-editor.org/info/rfc5322>.

[RFC5788] Melnikov, A. and D. Cridland, "IMAP4 Keyword Registry",
RFC 5788, DOI 10.17487/RFC5788, March 2010,
<https://www.rfc-editor.org/info/rfc5788>.

[RFC6154] Leiba, B. and J. Nicolson, "IMAP LIST Extension for
Special-Use Mailboxes", RFC 6154, DOI 10.17487/RFC6154,
March 2011, <https://www.rfc-editor.org/info/rfc6154>.

[RFC6409] Gellens, R. and J. Klensin, "Message Submission for Mail",
STD 72, RFC 6409, DOI 10.17487/RFC6409, November 2011,
<https://www.rfc-editor.org/info/rfc6409>.

[RFC6532] Yang, A., Steele, S., and N. Freed, "Internationalized
Email Headers", RFC 6532, DOI 10.17487/RFC6532, February
2012, <https://www.rfc-editor.org/info/rfc6532>.

[RFC6533] Hansen, T., Ed., Newman, C., and A. Melnikov,
"Internationalized Delivery Status and Disposition
Notifications", RFC 6533, DOI 10.17487/RFC6533, February
2012, <https://www.rfc-editor.org/info/rfc6533>.

[RFC6710] Melnikov, A. and K. Carlberg, "Simple Mail Transfer
Protocol Extension for Message Transfer Priorities",
RFC 6710, DOI 10.17487/RFC6710, August 2012,
<https://www.rfc-editor.org/info/rfc6710>.

[RFC7677] Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple
Authentication and Security Layer (SASL) Mechanisms",
RFC 7677, DOI 10.17487/RFC7677, November 2015,
<https://www.rfc-editor.org/info/rfc7677>.

[RFC8098] Hansen, T., Ed. and A. Melnikov, Ed., "Message Disposition
Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098,
February 2017, <https://www.rfc-editor.org/info/rfc8098>.

[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.

[RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete:
Use of Transport Layer Security (TLS) for Email Submission
and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018,
<https://www.rfc-editor.org/info/rfc8314>.

[RFC8457] Leiba, B., Ed., "IMAP "$Important" Keyword and
"\Important" Special-Use Attribute", RFC 8457,
DOI 10.17487/RFC8457, September 2018,
<https://www.rfc-editor.org/info/rfc8457>.

[RFC8474] Gondwana, B., Ed., "IMAP Extension for Object
Identifiers", RFC 8474, DOI 10.17487/RFC8474, September
2018, <https://www.rfc-editor.org/info/rfc8474>.

[RFC8620] Jenkins, N. and C. Newman, "The JSON Meta Application
Protocol", RFC 8620, DOI 10.17487/RFC8620, June 2019,
<https://www.rfc-editor.org/info/rfc8620>.

11.2. Informative References

[EFAIL] Poddebniak, D., Dresen, C., Mueller, J., Ising, F.,
Schinzel, S., Friedberger, S., Somorovsky, J., and J.
Schwenk, "Efail: Breaking S/MIME and OpenPGP Email
Encryption using Exfiltration Channels", August 2018,
<https://www.usenix.org/system/files/conference/
usenixsecurity18/sec18-poddebniak.pdf>.

[milter] Postfix, "Postfix before-queue Milter support", 2019,
<http://www.postfix.org/MILTER_README.html>.

[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003,
<https://www.rfc-editor.org/info/rfc3501>.

[RFC7489] Kucherawy, M., Ed. and E. Zwicky, Ed., "Domain-based
Message Authentication, Reporting, and Conformance
(DMARC)", RFC 7489, DOI 10.17487/RFC7489, March 2015,
<https://www.rfc-editor.org/info/rfc7489>.

[XCLIENT] Postfix, "Postfix XCLIENT Howto", 2019,
<http://www.postfix.org/XCLIENT_README.html>.

Authors' Addresses

Neil Jenkins
Fastmail
PO Box 234, Collins St. West
Melbourne, VIC 8007
Australia

Email: neilj@fastmailteam.com
URI: https://www.fastmail.com

Chris Newman
Oracle
440 E. Huntington Dr., Suite 400
Arcadia, CA 91006
United States of America

Email: chris.newman@oracle.com