EXTRAInternet Engineering Task Force (IETF) K. MurchisonInternet-DraftRequest for Comments: 8580 B. Gondwana Updates: 5230, 5435(if approved)FastMailIntended status:Category: Standards TrackJanuary 13, 2019 Expires: July 17,April 2019 ISSN: 2070-1721 Sieve Extension: File Carbon Copy(Fcc) draft-ietf-extra-sieve-fcc-09(FCC) Abstract The SieveEmail Filtering Languageemail filtering language provides a number of action commands, some of which can generate additional messages on behalf of the user. This document defines an extension to such commands to allow a copy of any generated message to be filed into a target mailbox. This document updatesRFC5230RFCs 5230 andRFC54355435 by adding a new tagged argument to the"vacation"Vacation and"enotify" actionsNotify actions, respectively. Status of This Memo ThisInternet-Draftissubmitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documentsan Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF).Note that other groups may also distribute working documents as Internet-Drafts. The listIt represents the consensus ofcurrent Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents validthe IETF community. It has received public review and has been approved fora maximumpublication 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 ofsix monthsthis document, any errata, and how to provide feedback on it may beupdated, replaced, or obsoleted by other documentsobtained atany time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on July 17, 2019.https://www.rfc-editor.org/info/rfc8580. Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 3. Tagged Argument ":fcc" . . . . . . . . . . . . . . . . . . . 3 3.1. Interaction withFileintoExtensions. . . . . . .to the Fileinto Action . . . 3 3.1.1. Imap4flags Extension . . . . . . . . . . . . . . . . 4 3.1.2. Mailbox Extension . . . . . . . . . . . . . . . . . . 4 3.1.3. Special-Use Extension . . . . . . . . . . . . . . . . 4 3.2. Collected Grammar . . . . . . . . . . . . . . . . . . . . 5 4. Format ofFile Carbon CopiedFCC Messages . . . . . . . . . . . . . . . . . . . 5 5. Interaction with the Vacation Action . . . . . . . . . . . . 6 6. Interaction with the Notify Action . . . . . . . . . . . . .67 6.1. Notification-Capability "fcc" . . . . . . . . . . . . . . 7 7. Compatibility with the Reject and Extended Reject Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8. Compatibility with Other Actions . . . . . . . . . . . . . . 8 9.Implementation Status . . . . . . . . . . . . . . . . . . . . 8 10.Security Considerations . . . . . . . . . . . . . . . . . . . 911.10. Privacy Considerations . . . . . . . . . . . . . . . . . . . 912.11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .10 12.1.9 11.1. Registration of New Sieve Extension . . . . . . . . . .. . 10 12.2.9 11.2. Registration of New Notification-Capability Parameter . . . . . . . . . . . . . . . . . . . . . . .10 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 14.9 12. References . . . . . . . . . . . . . . . . . . . . . . . . .11 14.1.10 12.1. Normative References . . . . . . . . . . . . . . . . . .11 14.2.10 12.2. Informative References . . . . . . . . . . . . . . . . .12 14.3. URIs . . . . . . . . . . . . . . . . . . . . .11 Acknowledgments . . . . .13 Appendix A. Change History (To be removed by RFC Editor before publication). . . . . . . . . . . . . . . . . . . .1312 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . .1512 1. Introduction The SieveEmail Filtering Languageemail filtering language [RFC5228] provides a number of action commands, some of which can generate additional messages on behalf of the user. It is sometimes desirable for a Sieve user to maintain an archive of the messages generated by these commands. This extension defines ":fcc", a new optional tagged argument":fcc" tofor action commands that generate additionalmessages to allowmessages. This argument allows a copy of the generated message to be filed into a target mailbox. The capability string associated with this extension is "fcc". Each new action that generates additional messages will need to specify how it interacts with:fcc.the FCC extension. This document specifies the interaction of:fccthe FCC extension with the Vacation [RFC5230] and Notify [RFC5435]extensions.actions. 2. Conventions Used in This Document Conventions for notations are as described in Section 1.1 of [RFC5228], including use of the "Usage:" label for the definition of the action and the syntax of taggedarguments syntax.arguments. 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[1][RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. Tagged Argument ":fcc" This document specifies ":fcc", a new optional tagged argument":fcc"that alters the behavior of action commands that generate additional messages on behalf of the user. Usage: :fcc <mailbox: string> The:fcc":fcc" tagged argument instructs the Sieve interpreter to file a copy of the generated message into the mailbox provided in the subsequent argument. The semantics and treatment of the mailbox argument are defined to match those of the mailbox argument to the"fileinto"fileinto action specified in Section 4.1 of [RFC5228]. Specifically, use of an invalid mailbox name MAY be treated as an error or result in delivery to an implementation-defined mailbox, and if the specified mailbox doesn't exist, the implementation MAY treat it as an error, create the mailbox, or file the message into an implementation-defined mailbox. 3.1. Interaction withFileintoExtensions to the Fileinto Action Some tagged arguments defined in extensions to the"fileinto"fileinto action can be used together with":fcc".the ":fcc" tagged argument. The sections below describe these interactions. Tagged arguments in future extensions to the"fileinto"fileinto action need to describe their interaction with":fcc",the FCC extension, if any. When any"fileinto"fileinto extension arguments are used with":fcc",the FCC extension, the corresponding extension MUST be enabled, and the arguments are defined to have the same syntax, semantics, and treatment as they do with"fileinto".the fileinto action. 3.1.1. Imap4flags Extension This document extends the definition of the ":flags" tagged argument (see Section 5 of [RFC5232]) so that it can optionally be used with the ":fcc" tagged argument. Usage: :fcc <mailbox: string> [:flags <list-of-flags: string-list>] If the optional ":flags" tagged argument is specified with":fcc",the ":fcc" tagged argument, it instructs the Sieve interpreter to set the IMAP4 flags provided in the subsequent argument when the generated message is filed into the target mailbox. 3.1.2. Mailbox Extension This document extends the definition of the ":create" tagged argument (see Section 3.2 of [RFC5490]) so that it can optionally be used with the ":fcc" tagged argument. Usage: :fcc <mailbox: string> [:create] If the optional ":create" tagged argument is specified with":fcc",the ":fcc" tagged argument, it instructs the Sieve interpreter to create the target mailbox, if needed, before attempting to file the generated message into the target mailbox. 3.1.3. Special-Use Extension This document extends the definition of the ":specialuse" tagged argument (see Section 4 of[I-D.ietf-extra-sieve-special-use])[RFC8579]) so that it can optionally be used with the ":fcc" tagged argument. Usage: :fcc <mailbox: string> [:specialuse <special-use-flag: string>] If the optional ":specialuse" tagged argument is specified with":fcc",the ":fcc" tagged argument, it instructs the Sieve interpreter to check whether a mailbox exists with the specific special-use flag assigned to it. If such a mailbox exists, the generated message is filed into the special-use mailbox. Otherwise, the generated message is filed into the target mailbox. Ifboththe optional ":specialuse" and ":create" tagged arguments are both specified with":fcc",the ":fcc" tagged argument, the Sieve interpreter is instructed to create the target mailbox per Section 4.1 of[I-D.ietf-extra-sieve-special-use],[RFC8579], if needed. 3.2. Collected Grammar For convenience, the "FCC" syntax element is defined here using ABNF [RFC5234] so that it can be augmented by other extensions. Note that the following is the grammar of "FCC" after it has been lexically interpreted. No whitespace or comments appear below. FCC = ":fcc" string *FCC-OPTS ; per Section 2.6.2 ofRFC5228,RFC 5228, ; the tagged arguments in FCC may appear in any order FCC-OPTS = CREATE / IMAP-FLAGS / SPECIAL-USE ; each option MUST NOT appear more than once CREATE = ":create" IMAP-FLAGS = ":flags" string-list SPECIAL-USE = ":specialuse" string 4. Format ofFile Carbon CopiedFCC Messages Copies of messages filed into a mailbox via this extension are REQUIRED to be in the Internet Message Format [RFC5322]. Some messages generated by Sieve actions might already conform to this format and MAY be filed without modification. Messages generated in other formats MUST be encapsulated using constructs from the Internet Message Format [RFC5322] and MIME ([RFC2045], [RFC2046], [RFC2047], [RFC2231]). The general requirements for encapsulating the copies of messages to be filed arethe following:as follows: o Date: The Date header field is REQUIRED and SHOULD be set to the date and time when the message was generated. o From: The From header field is REQUIRED and SHOULD be set to the email address of the owner of the Sieve script, unless explicitly overridden by rules for encapsulating a particular message type. Per Erratum ID 2035 [Err2035], "Informative advice: Users often have multiple email addresses, and "the email address of the owner of the Sieve script" may offer a choice among several. If the sieve processor recognizes an address belonging to the owner of the Sieve script in the To or Cc fields of the input message, then it's better to use that address for the From field of the generated message, rather than any other addresses the script's owner may also have". o To: The To header field is OPTIONAL and MAY be set to the email address of the recipient of the generated message, if available. o Subject: The Subject header field is OPTIONAL and MAY be generatedas follows: Theby setting the subjectis setto the characters "Fcc: " followed by the subject of the message being processed by the Sieve interpreter. o In-Reply-To: The In-Reply-To header field is OPTIONAL and MAY be set to the Message-ID of the message being processed by the Sieve interpreter. o Message Body: The body of the filed message is REQUIRED and is composed of one or moreMIME-partsMIME parts containing the generated message and any related metadata. The Content-Type header field(s) MUST be set to the appropriate MIME types. If any of theMIME-partsMIME parts include 8-bit or binary data, the Content-Transfer- Encoding header field(s) MUST be set accordingly. 5. Interaction with the Vacation Action This document extends the"vacation"Vacation [RFC5230] action (see also"vacation-seconds" [RFC6131])"Seconds" parameter [RFC6131] to optionally store a copy of the auto- reply messages into a target mailbox. Usage: vacation [FCC] [":days" number | ":seconds" number] [":subject" string] [":from" string] [":addresses" string-list] [":mime"] [":handle" string] <reason: string> Example(with(using fileinto extensions): require ["vacation", "fcc", "mailbox", "special-use", "imap4flags"]; vacation :days 7 :from "hemingway@example.com" "Gone Fishin'" :specialuse "\\Sent" :create :fcc "INBOX.Sent" :flags ["\\Seen"]; Vacation auto-reply messages areMIME-compliantcompliant with MIME and can be filed into the target mailbox without modification. 6. Interaction with the Notify Action This document extends the"notify"Notify [RFC5435] action to optionally store a copy of the notification messages into a target mailbox. Usage: notify [FCC] [":from" string] [":importance" <"1" / "2" / "3">] [":options" string-list] [":message" string] <method: string> Example: require ["enotify", "fcc"]; notify :fcc "INBOX.Sent" :message "You got mail!" "mailto:ken@example.com"; Messages generated using the "mailto" [RFC5436] notification method areMIME-compliantcompliant with MIME and can be filed into the target mailbox without modification. Messages generated by other notification methods(e.g.(e.g., "xmpp" [RFC5437]) MUST be encapsulated per Section 4 before being filed. The body of the filed message MUST include the:message parameter":message" tagged argument and MAY include one or more of the:from, :importance,":from", ":importance", or:options parameters.":options" tagged arguments. TheMIME-type(s)MIME type(s) of the body part(s) used to encapsulate the parameters is an implementation decision. An implementation MAY only support:fccthe FCC extension in conjunction with a subset of the notification methods it supports. An error occurs if:fccthe FCC extension iscombinedused with a notification method that doesn't support it. Notification methods that support:fccthe FCC extension can be discovered atrun-timeruntime using the mechanism describedbelow (Section 6.1).in Section 6.1. 6.1. Notification-Capability "fcc" This document defines "fcc", a new notification-capability value"fcc"for use with the notify_method_capability test (see Section 5 of [RFC5435]. For the "fcc" notification-capability, the notify_method_capability test can match one of the following key-list values: yes A copy of the notification message sent using the method identified by the notification-uri can be filed into a target mailbox. no A copy of the notification message sent using the method identified by the notification-urican notcannot be filed into a target mailbox. Note that the "fcc" notify_method_capability test does not require the notification-uri argument to specify anything other than a scheme. Example: require ["enotify", "fcc"]; if notify_method_capability "xmpp:" "fcc" "yes" { notify :fcc "INBOX.Sent" :message "You got mail" "xmpp:ken@example.com?message;subject=SIEVE"; } else { notify :fcc "INBOX.Sent" :message "You got mail!" "mailto:ken@example.com"; } 7. Compatibility with the Reject and Extended Reject Actions Implementations MUST NOT allow use of"fcc"the FCC extension with the"reject"reject and"ereject"ereject [RFC5429] actions. Allowing"fcc"use of the FCC extension with these actions would violate the SMTP [RFC5321] principle that a message is either delivered or bounced back to the sender. Namely, the saved copy of the rejection message will contain the original message. It is an error for a script to use the ":fcc" tagged argument with either"reject"of the reject or"ereject".ereject actions. 8. Compatibility with Other Actions The"fcc"FCC extension is not compatible with any Sieve action that does not generate an additional message on behalf of the user. It is an error for a script to use the ":fcc" tagged argument with any such action. Future extensions that define actions that generate additional messages on behalf of the user need to describe their compatibility with":fcc",the FCC extension and describe how to MIME-encapsulate the message, if required.10.9. Security Considerations In addition to the security considerations in [RFC5228], [RFC5230], [RFC5435], and [RFC6131], it should be noted that filing copies of generated messages may cause the Sieve script owner to exceedtheirthe allocated storage (quota) on the mail system, thereby preventing delivery of future messages destined for the owner.11.10. Privacy Considerations In addition to the privacy considerations in [RFC5228], [RFC5230], [RFC5435], and [RFC6131], it should be noted that a copy of a generated message filed into a shared or publicmaiboxmailbox (as opposed to a private mailbox) could expose private information about the Sieve script owner to third parties. For instance, users that have access to the shared/public mailbox might discover that the Sieve script owner is on holiday or might discover the owner's physical location.12.11. IANA Considerations12.1.11.1. Registration of New Sieve ExtensionTo: iana@iana.org Subject: Registration of newIANA has registered the following Sieve extension in the "Sieve Extensions" registry at <https://www.iana.org/assignments/sieve- extensions>: Capability name: fcc Description: Adds the ":fcc" parameter to Sieve action commands that generate additional messages. RFC number: RFCXXXX8580 Contact address: The Sieve discussion list <sieve@ietf.org>12.2.11.2. Registration of New Notification-Capability ParameterTo: iana@iana.org Subject: Registration of a newIANA has registered the following notification-capability parameter in the "Notification-Capability Parameters" registry at <https://www.iana.org/assignments/notification-capability- parameters>: Capabilityname:Name: fcc Description: Returns whether a copy of the notification message sent using the method identified by the notification-uri parameter to the notify_method_capability test can be filed into a target mailbox. Syntax: Can contain one of two values: "yes" or "no". Values MUST be in lowercase.Permanent and readily available reference(s): ThisReference: RFCContact information:8580 Contact: The Sieve discussion list<ietf-mta- filters@imc.org> 14.<sieve@ietf.org> 12. References14.1.12.1. Normative References[I-D.ietf-extra-sieve-special-use] Bosch, S., "Sieve Email Filtering: Delivering to Special- Use Mailboxes", draft-ietf-extra-sieve-special-use-04 (work in progress), November 2018.[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>. [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, DOI 10.17487/RFC2046, November 1996, <https://www.rfc-editor.org/info/rfc2046>. [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>. [RFC5228] Guenther, P., Ed. and T. Showalter, Ed., "Sieve: An Email Filtering Language", RFC 5228, DOI 10.17487/RFC5228, January 2008, <https://www.rfc-editor.org/info/rfc5228>. [RFC5230] Showalter, T. and N. Freed, Ed., "Sieve Email Filtering: Vacation Extension", RFC 5230, DOI 10.17487/RFC5230, January 2008, <https://www.rfc-editor.org/info/rfc5230>. [RFC5232] Melnikov, A., "Sieve Email Filtering: Imap4flags Extension", RFC 5232, DOI 10.17487/RFC5232, January 2008, <https://www.rfc-editor.org/info/rfc5232>. [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/RFC5234, January 2008, <https://www.rfc-editor.org/info/rfc5234>. [RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322, DOI 10.17487/RFC5322, October 2008, <https://www.rfc-editor.org/info/rfc5322>. [RFC5429] Stone, A., Ed., "Sieve Email Filtering: Reject and Extended Reject Extensions", RFC 5429, DOI 10.17487/RFC5429, March 2009, <https://www.rfc-editor.org/info/rfc5429>. [RFC5435] Melnikov, A., Ed., Leiba, B., Ed., Segmuller, W., and T. Martin, "Sieve Email Filtering: Extension for Notifications", RFC 5435, DOI 10.17487/RFC5435, January 2009, <https://www.rfc-editor.org/info/rfc5435>. [RFC5490] Melnikov, A., "The Sieve Mail-Filtering Language -- Extensions for Checking Mailbox Status and Accessing Mailbox Metadata", RFC 5490, DOI 10.17487/RFC5490, March 2009, <https://www.rfc-editor.org/info/rfc5490>. [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>.14.2.[RFC8579] Bosch, S., "Sieve Email Filtering: Delivering to Special- Use Mailboxes", RFC 8579, DOI 10.17487/RFC8579, April 2019, <https://www.rfc-editor.org/info/rfc8579>. 12.2. Informative References [Err2035] RFC Errata, Errata ID 2035, RFC 5230, <https://www.rfc-editor.org/errata_search.php?eid=2035>. [RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, DOI 10.17487/RFC5321, October 2008, <https://www.rfc-editor.org/info/rfc5321>. [RFC5436] Leiba, B. and M. Haardt, "Sieve Notification Mechanism: mailto", RFC 5436, DOI 10.17487/RFC5436, January 2009, <https://www.rfc-editor.org/info/rfc5436>. [RFC5437] Saint-Andre, P. and A. Melnikov, "Sieve Notification Mechanism: Extensible Messaging and Presence Protocol (XMPP)", RFC 5437, DOI 10.17487/RFC5437, January 2009, <https://www.rfc-editor.org/info/rfc5437>. [RFC6131] George, R. and B. Leiba, "Sieve Vacation Extension: "Seconds" Parameter", RFC 6131, DOI 10.17487/RFC6131, July 2011, <https://www.rfc-editor.org/info/rfc6131>.13.Acknowledgments The authors would like to thank the following individuals for contributing their ideas andsupport for writingsupporting this specification: Ned Freed, Stan Kalisch, and Alexey Melnikov. Authors' Addresses Kenneth Murchison FastMail US LLC 1429 WalnutStreet -Street, Suite 1201 Philadelphia, PA 19102USAUnited States of America Email: murch@fastmailteam.com Bron Gondwana FastMail Pty Ltd Level 2, 114 William Street Melbourne, VIC 3000 Australia Email: brong@fastmailteam.com