|Internet-Draft||Sieve Process iMIP||January 2023|
|Murchison, et al.||Expires 14 July 2023||[Page]|
- Network Working Group
- Intended Status:
- Standards Track
Sieve Email Filtering: Extension for Processing iMIP Messages
This document describes the "processimip" extension to the Sieve email filtering language. The "processimip" extension gives Sieve the ability to process messages using the iCalendar Message-Based Interoperability Protocol (iMIP).¶
- The Cyrus implementation used at Fastmail also adds an :invitesonly option to the processimip action in order to emulate existing functionality elsewhere within our stack. Is there any interest in formalizing this option? This may be superfluous as it might not make sense to auto-process an initial invitation but then NOT auto-process future updates to an event.¶
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Copyright (c) 2023 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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
Users typically receive invites, replies, and cancelations for events, tasks, etc. via Internet mail messages. It is sometimes desirable to have such messages automatically parsed and the attached iCalendar [RFC5545] objects added to, updated on, or deleted from the user's calendars.¶
This document defines an extension to the Sieve language [RFC5228] that enables scripts to process messages using the iCalendar Message-Based Interoperability Protocol (iMIP) [RFC6047]. Specifically, this extension provides the ability to alter iCalendar objects on a user's calendars referenced in iMIP messages.¶
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.¶
Sieve interpreters that implement this extension have an identifier of "processimip" for use with the capability mechanism.¶
Usage: processimip [ :addresses <string-list> ] [ :updatesonly | :calendarid <string> ] [ :deletecanceled ] [ :outcome <variablename: string> ] [ :errstr <variablename: string> ]¶
The "processimip" action can be used with or without the "variables" [RFC5229] extension. When the "variables" extension is enabled in a script using <require "variables">, the script can use the ":outcome" (Section 4.5) and ":errstr" (Section 4.6) arguments to the "processimip" action described below. When the "variables" extension is not enabled, the ":outcome" and ":errstr" arguments MUST NOT be used and MUST cause an error according to [RFC5228].¶
"processimip" MUST NOT process a message unless it is a well-formed iMIP message and one of the recipient user's email addresses matches the Calendar User Address (see Section 3.3.3 of [RFC5545]) of the intended target of the message, as determined by the iTIP method (see Section 1.4 of [RFC5546]) of the message:¶
- "REPLY": Value of the "Organizer" property (see Section 188.8.131.52 of [RFC5545])¶
- "REQUEST", "CANCEL", "ADD": Value of one of the "Attendee" properties (see Section 184.108.40.206 of [RFC5545])¶
The recipient user's email address matches the Calender User Address of the target if the Calendar User Address is in the form of a mailto URI and the email address matches the "addr-spec" of the URI.¶
An email address is considered to belong to the recipient if it is one of:¶
- an email address known by the implementation to be associated with the recipient,¶
- the final envelope recipient address if it's available to the implementation, or¶
- an address specified by the script writer via the :addresses (Section 4.1) argument.¶
The "processimip" action does not cancel the implicit keep.¶
The optional :addresses argument is used to specify email addresses that belong to the recipient in addition to the addresses known to the implementation.¶
The optional :updatesonly argument is used to limit the messages processed to those targeting existing iCalendar objects only. If the message contains a new iCalendar object (initial invitation), the implementation MUST NOT add the object to a calendar.¶
If :updatesonly is omitted, new iCalendar objects (initial invitations) may be added to one of the user's calendars.¶
The optional :calendarid argument specifies the identifier of the calendar onto which new iCalendar objects (initial invitations) should placed.¶
If :calendarid is omitted, new iCalendar objects will be placed on the user's "default" calendar as determined by the implementation.¶
The optional :deletecanceled argument is used to tell the implementation that if it receives a cancelation message, it should remove the associated iCalendar object from the calendar.¶
If :deletecanceled is omitted, the associated iCalendar object will be marked as canceled and will remain on the calendar.¶
The optional :outcome argument specifies the name of a variable into which one of the following strings specifying the outcome of the action will be stored:¶
- "no_action": No action was performed (E.g., the message wasn't an iMIP message, or the message contained a new iCalendar object but the ":updatesonly" argument was used)¶
- "added": A new iCalendar object was added to a calendar¶
- "update": An iCalendar resource was updated or canceled¶
- "error": An error processing the iMIP message occurred¶
The optional :errstr argument specifies the name of a variable into which a string describing the reason for the outcome will be stored.¶
This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in [RFC7942]. The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist.¶
According to [RFC7942], "this will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. It is up to the individual working groups to use this information as they see fit".¶
The open source Cyrus Server project is a highly scalable enterprise mail system which supports Sieve email filtering at the point of final delivery. This production level Sieve implementation supports all of the requirements described in this document. This implementation is freely distributable under a BSD style license from Computing Services at Carnegie Mellon University.¶
TODO: Discuss calendar SPAM.¶
This document defines the following new Sieve extension to be added to the registry defined in Section 6.2 of [RFC5228] and located here: https://www.iana.org/assignments/sieve-extensions/sieve-extensions.xhtml#sieve-extensions¶
IANA are requested to add a capability to the Sieve Extensions registry:¶
The authors would like to thank the following individuals for contributing their ideas and support for writing this specification: Ned Freed and Alexey Melnikov.¶
- Bradner, S. and RFC Publisher, "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
- Guenther, P., Ed. and T. Showalter, Ed., "Sieve: An Email Filtering Language", RFC 5228, DOI 10.17487/RFC5228, , <https://www.rfc-editor.org/info/rfc5228>.
- Homme, K., "Sieve Email Filtering: Variables Extension", RFC 5229, DOI 10.17487/RFC5229, , <https://www.rfc-editor.org/info/rfc5229>.
- Melnikov, A., Ed., "iCalendar Message-Based Interoperability Protocol (iMIP)", RFC 6047, DOI 10.17487/RFC6047, , <https://www.rfc-editor.org/info/rfc6047>.
- Leiba, B. and RFC Publisher, "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
- Desruisseaux, B., Ed., "Internet Calendaring and Scheduling Core Object Specification (iCalendar)", RFC 5545, DOI 10.17487/RFC5545, , <https://www.rfc-editor.org/info/rfc5545>.
- Daboo, C., Ed., "iCalendar Transport-Independent Interoperability Protocol (iTIP)", RFC 5546, DOI 10.17487/RFC5546, , <https://www.rfc-editor.org/info/rfc5546>.
- Sheffer, Y. and A. Farrel, "Improving Awareness of Running Code: The Implementation Status Section", BCP 205, RFC 7942, DOI 10.17487/RFC7942, , <https://www.rfc-editor.org/info/rfc7942>.
Changes since draft-murchison-sieve-processimip-01:¶
- No changes.¶
Changes since draft-murchison-sieve-processimip-00:¶
- Document name change only.¶