EXTRA
Internet Engineering Task Force (IETF) B. Gondwana, Ed.
Internet-Draft
Request for Comments: 9042 Fastmail
Updates: 5228 (if approved) 16 March June 2021
Intended status:
Category: Standards Track
Expires: 17 September 2021
ISSN: 2070-1721
Sieve Email Filtering: delivery Delivery by mailboxid
draft-ietf-extra-sieve-mailboxid-09 MAILBOXID
Abstract
The OBJECTID capability of the IMAP protocol (RFC8474) (RFC 8474) allows clients to identify
mailboxes by a unique identifier which that survives rename. renaming.
This document extends the Sieve mail email filtering language (RFC5228) (RFC 5228)
to allow using that same unique identifier as a target for fileinto
rules,
rules and for testing the existance existence of mailboxes.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 17 September 2021.
https://www.rfc-editor.org/info/rfc9042.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used In in This Document . . . . . . . . . . . . . . 3
3. Sieve capability string . . . . . . . . . . . . . . . . . . . 3 Capability String
4. Argument ":mailboxid" :mailboxid to Command "fileinto" . . . . . . . . . 3 fileinto
4.1. Interaction with "mailbox" extension . . . . . . . . . . 4 Mailbox Extension
4.2. Interaction with "specialuse" extension . . . . . . . . . 4 Special-Use Extension
5. Interaction with "fcc" extension . . . . . . . . . . . . . . 5 FCC Extension
6. Test "mailboxidexists" . . . . . . . . . . . . . . . . . . . 5 mailboxidexists
7. Interaction with variables extension . . . . . . . . . . . . 6 Variables Extension
8. Security considerations . . . . . . . . . . . . . . . . . . . 6 Considerations
9. IANA considerations . . . . . . . . . . . . . . . . . . . . . 6 Considerations
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
11. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. draft-ietf-sieve-mailboxid-09 . . . . . . . . . . . . . 7
11.2. draft-ietf-sieve-mailboxid-08 . . . . . . . . . . . . . 7
11.3. draft-ietf-sieve-mailboxid-07 . . . . . . . . . . . . . 7
11.4. draft-ietf-sieve-mailboxid-06 . . . . . . . . . . . . . 8
11.5. draft-ietf-sieve-mailboxid-05 . . . . . . . . . . . . . 8
11.6. draft-ietf-sieve-mailboxid-04 . . . . . . . . . . . . . 8
11.7. draft-ietf-sieve-mailboxid-03 . . . . . . . . . . . . . 8
11.8. draft-ietf-sieve-mailboxid-02 . . . . . . . . . . . . . 8
11.9. draft-ietf-sieve-mailboxid-01 . . . . . . . . . . . . . 8
11.10. draft-ietf-sieve-mailboxid-00 . . . . . . . . . . . . . 8
11.11. draft-gondwana-sieve-mailboxid-02 . . . . . . . . . . . 9
11.12. draft-gondwana-sieve-mailboxid-01 . . . . . . . . . . . 9
11.13. draft-gondwana-sieve-mailboxid-00 . . . . . . . . . . . 9
12. References
10.1. Normative References . . . . . . . . . . . . . . . . . . . . 9
13.
10.2. Informative References . . . . . . . . . . . . . . . . . . . 10
Acknowledgements
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
[RFC5228]
Sieve rules [RFC5228] are sometimes created using graphical
interfaces
interfaces, which allow users to select the mailbox to be used as a
target for a rule.
If that mailbox is renamed, the client may also update its internal
representation of the rule and update the sieve Sieve script to match,
however match;
however, this is a multi-step multistep process and subject to partial failures.
Also, if the folder is renamed by a different mechanism (e.g. (e.g.,
another IMAP client) client), the rules will get out of sync.
By telling "fileinto" fileinto to reference the immutable mailboxid MAILBOXID specified by
[RFC8474], using the extension specified herein, sieve Sieve rules can
continue to target the same mailbox mailbox, even if it gets renamed.
2. Conventions Used In in This Document
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.
3. Sieve capability string Capability String
Scripts which that use the following extensions defined in this document MUST
explicitly require the capability "mailboxid".
Example:
require "mailboxid";
4. Argument ":mailboxid" :mailboxid to Command "fileinto" fileinto
Normally, the "fileinto" fileinto command delivers the message in the mailbox
specified using its positional mailbox argument. However, if the
optional ":mailboxid" :mailboxid argument is also specified, the "fileinto" fileinto command
first checks whether a mailbox exists in the user's personal
namespace [RFC2342] with the specified [RFC8474] MAILBOXID. MAILBOXID [RFC8474].
If a matching mailbox is found, that mailbox is used for delivery.
If there is no such mailbox, the "fileinto" fileinto action proceeds as it would
without the ":mailboxid" :mailboxid argument.
The tagged argument ":mailboxid" :mailboxid to fileinto consumes one additional
token, a string with containing the objectid OBJECTID of the mailbox to file into. target mailbox.
Example:
require "fileinto";
require "mailboxid";
if header :contains ["from"] "coyote" {
fileinto :mailboxid "F6352ae03-b7f5-463c-896f-d8b48ee3"
"INBOX.harassment";
}
4.1. Interaction with "mailbox" extension Mailbox Extension
For servers which that also support the [RFC5490] mailbox extension, extension defined in
[RFC5490], if both the ":create" :create and ":mailboxid" :mailboxid arguments are provided
to a
"fileinto" fileinto command and no matching mailbox is found, then a new
mailbox will be created.
This new mailbox will have the name specified by the positional
mailbox argument ([RFC5228] section 4.1), however ([RFC5228], Section 4.1); however, it will get a
different mailboxid MAILBOXID (chosen by the server) rather than the one
specified by the ":mailboxid" :mailboxid argument to fileinto.
Example:
require "fileinto";
require "mailboxid";
require "mailbox";
fileinto :mailboxid "Fnosuch"
:create
"INBOX.no-such-folder";
# creates INBOX.no-such-folder, but it doesn't
# get the "Fnosuch" mailboxid.
4.2. Interaction with "specialuse" extension Special-Use Extension
For servers which that also support [RFC8579] delivery to special-use
mailboxes, mailboxes
[RFC8579], it is an error to specify both ":mailboxid" :mailboxid and
":specialuse" :specialuse
in the same fileinto command.
Advanced filtering based on both special-use and mailboxid MAILBOXID can be
built with explicit "specialuse_exists" specialuse_exists and "mailboxidexists" mailboxidexists tests.
| Note to developers of sieve Sieve generation tools: it
|
| It is advisable to use special-use rather than mailboxid MAILBOXID when
| creating rules that are based on a special-use purpose (e.g. (e.g.,
| delivery directly to the Junk folder based on a header that was
| added by a scanning agent earlier in the
mailflow). mail flow).
5. Interaction with "fcc" extension FCC Extension
This document extends the definition of the ":fcc" :fcc argument defined in
[RFC8580] so that it can optionally be used with the ":mailboxid" :mailboxid
argument. The syntax for "FCC" FCC is extended here using ABNF [RFC5234]:
MAILBOXID-OPT = ":mailboxid" objectid
FCC-OPTS =/ MAILBOXID-OPT
If the optional ":mailboxid" :mailboxid argument is specified with ":fcc", :fcc, it
instructs the Sieve interpreter to check whether a mailbox exists
with the specific mailboxid. MAILBOXID. If such a mailbox exists, the generated
message is filed into that mailbox. Otherwise, the generated message
is filed into the ":fcc" :fcc target mailbox.
As with fileinto, it is an error to specify both ":mailboxid" :mailboxid and
":specialuse"
:specialuse for the same fcc rule.
Example:
require ["enotify", "fcc", "mailboxid"];
notify :fcc "INBOX.Sent"
:mailboxid "F6352ae03-b7f5-463c-896f-d8b48ee3"
:message "You got mail!"
"mailto:ken@example.com";
6. Test "mailboxidexists" mailboxidexists
Usage: mailboxidexists <mailbox-objectids: string-list>
The "mailboxidexists" mailboxidexists test is true if all mailboxes listed in the
"mailboxids" every string argument exist provided is
the MAILBOXID of a mailbox that exists in the mailstore, mailstore and each that
allows the user in whose context the Sieve script runs to "deliver" deliver
messages into it.
When the mailstore is an IMAP server, "delivery" of
messages server that also supports IMAP Access
Control List (ACL) [RFC4314], delivery is possible if:
a) allowed if the READ-WRITE response code is present user has the
'p' or 'i' rights for the mailbox (see Section 7.1 5.2 of [RFC3501]), if IMAP Access Control List (ACL)
[RFC4314] [RFC4314]).
When the mailstore is an IMAP server that does not supported by the server, or
b) support IMAP ACL,
delivery is allowed if the user has 'p' or 'i' rights READ-WRITE response code is present for
the mailbox when selected by the user (see Section 5.2 7.1 of
[RFC4314]). [RFC3501]).
Note that a successful "mailboxidexists" mailboxidexists test for a mailbox doesn't
necessarily mean that a "fileinto :mailboxid" action on this mailbox
would succeed. For example, the "fileinto" fileinto action might put the user
over quota. The "mailboxidexists" mailboxidexists test only verifies existence of the
mailbox and whether the user in whose context the Sieve script runs
has permissions to execute "fileinto" fileinto on it.
Example:
require "fileinto";
require "mailboxid";
if header :contains ["from"] "coyote" {
if mailboxidexists "F6352ae03-b7f5-463c-896f-d8b48ee3" {
fileinto :mailboxid "F6352ae03-b7f5-463c-896f-d8b48ee3"
"INBOX.name.will.not.be.used";
} else {
fileinto "INBOX.harassment";
}
}
| Note to implementers: this
|
| This test behaves identically to the
"mailboxexists" mailboxexists test defined
| in [RFC5490] but operates on mailboxids MAILBOXIDs rather than mailbox
| names.
7. Interaction with variables extension Variables Extension
There is no special interaction defined, however defined; however, as an objectid OBJECTID is a
string in this document, objectid OBJECTID values can contain variable
expansions if [RFC5229] is enabled.
8. Security considerations Considerations
Because mailboxid MAILBOXID is always generated by the server, implementations
MUST NOT allow sieve Sieve to make an endrun end run around this protection by
creating mailboxes with the specified ID by using ":create" :create and
":mailboxid"
:mailboxid in a fileinto rule for a non-existant nonexistent mailbox.
Implementers are referred to the security considerations Security Considerations sections of
[RFC5228] and [RFC8474].
9. IANA considerations Considerations
IANA are requested to add a has added the following capability to the sieve-extensions
registry:
To: iana@iana.org
Subject: Registration of new Sieve extension "Sieve Extensions"
registry at <https://www.iana.org/assignments/sieve-extensions>:
Capability name: mailboxid
Description: adds a test for checking mailbox existence by objectid, OBJECTID
and new optional arguments to fileinto and :fcc which that allow
selecting the destination mailbox by objectid. OBJECTID.
RFC number: this RFC 9042
Contact address: The EXTRA discussion list <extra@ietf.org>
10. Acknowledgements
This document borrows heavily from [RFC5490] for the matching
mailboxexists test, and from [RFC8579] for an example of modifying
the fileinto command.
Thanks to Ned Freed and Ken Murchison and Alexey Melnikov for
feedback on the EXTRA mailing list.
11. Changes
(EDITOR: remove this section before publication)
11.1. draft-ietf-sieve-mailboxid-09
* update FCC-OPTS to have an intermediate production for the
:mailboxid option, and reference "objectid" from RFC8474 as the
valid format for the option value.
11.2. draft-ietf-sieve-mailboxid-08
* IETF110 discussion - re-add FCC-OPTS syntax, and clarify that
:mailboxid is incompatible with :specialuse to parallel the
fileinto behaviour
11.3. draft-ietf-sieve-mailboxid-07
* Martin Duke review - remove formal section
* Martin Duke review - wording References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for section 4.1 (interaction with
:create)
* Ken Murchison review - fixed :special-use to :specialuse per
RFC8579
11.4. draft-ietf-sieve-mailboxid-06
* GENART review - fixed example to not be semantically pointless
* GENART review - fixed !@ to @! in RFC reference mmark syntax
11.5. draft-ietf-sieve-mailboxid-05
* disallow :mailboxid and :special-use in the same fileinto action.
11.6. draft-ietf-sieve-mailboxid-04
* made RFC5490 and RFC8579 normative
* clarified wording based on AD feedback from Barry
11.7. draft-ietf-sieve-mailboxid-03
* Fixed ABNF syntax error
11.8. draft-ietf-sieve-mailboxid-02
* removed bogus : from "mailboxidexists" test title
* moved FCC to its own top-level section since it is not used with
the fileinto command.
11.9. draft-ietf-sieve-mailboxid-01
* fixed idnits - RFC5228 not mentioned use in the abstract
* fixed other I-D references I had missed, oops
11.10. draft-ietf-sieve-mailboxid-00
* Adopted into working group per adoption call on list
* Updated references to old drafts which have since been published.
* Fixed some typoes and simplified some language.
* Removed stray leading colon on mailboxexists (thanks Alexey)
* Added :fcc to the IANA registration description (thanks Alexey)
* Mentioned that variables can be expanded (thanks Alexey)
11.11. draft-gondwana-sieve-mailboxid-02
* Update document date by a couple of years! Ooops, it got
forgotten after a WGLC which got not dissent.
* Create xml2rfc v3 output.
11.12. draft-gondwana-sieve-mailboxid-01
* Switch RFCs to :mailboxid tagged parameter value with fallback mailbox
name.
* Document interaction with "mailbox".
* Document interaction with "special-use".
* Document interaction with "fcc".
* Document security considerations around :mailboxid Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2342] Gahrns, M. and :create.
11.13. draft-gondwana-sieve-mailboxid-00
* Initial version.
12. Normative References C. Newman, "IMAP4 Namespace", RFC 2342,
DOI 10.17487/RFC2342, May 1998,
<https://www.rfc-editor.org/info/rfc2342>.
[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>.
[RFC8474] Gondwana, B., Ed., "IMAP Extension for Object
Identifiers", RFC 8474, DOI 10.17487/RFC8474, September
2018, <https://www.rfc-editor.org/info/rfc8474>.
[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>.
[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>.
[RFC2119] Bradner, S., "Key words for use
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFCs to Indicate
Requirement Levels", RFC
2119 Key Words", BCP 14, RFC 2119, 8174, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2342] Gahrns, M. and C. Newman, "IMAP4 Namespace", 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8474] Gondwana, B., Ed., "IMAP Extension for Object
Identifiers", RFC 2342, 8474, DOI 10.17487/RFC2342, May 1998,
<https://www.rfc-editor.org/info/rfc2342>. 10.17487/RFC8474, September
2018, <https://www.rfc-editor.org/info/rfc8474>.
[RFC8580] Murchison, K. and B. Gondwana, "Sieve Extension: File
Carbon Copy (FCC)", RFC 8580, DOI 10.17487/RFC8580, May
2019, <https://www.rfc-editor.org/info/rfc8580>.
13.
10.2. Informative References
[RFC8579] Bosch, S., "Sieve Email Filtering: Delivering to Special-
Use Mailboxes", RFC 8579, DOI 10.17487/RFC8579, May 2019,
<https://www.rfc-editor.org/info/rfc8579>.
[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>.
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003,
<https://www.rfc-editor.org/info/rfc3501>.
[RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension",
RFC 4314, DOI 10.17487/RFC4314, December 2005,
<https://www.rfc-editor.org/info/rfc4314>.
[RFC5229] Homme, K., "Sieve Email Filtering: Variables Extension",
RFC 5229, DOI 10.17487/RFC5229, January 2008,
<https://www.rfc-editor.org/info/rfc5229>.
[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>.
[RFC8579] Bosch, S., "Sieve Email Filtering: Delivering to Special-
Use Mailboxes", RFC 8579, DOI 10.17487/RFC8579, May 2019,
<https://www.rfc-editor.org/info/rfc8579>.
Acknowledgements
This document borrows heavily from [RFC5490] for the matching
mailboxexists test and from [RFC8579] for an example of modifying the
fileinto command.
Thanks to Ned Freed, Ken Murchison, and Alexey Melnikov for feedback
on the EXTRA mailing list.
Author's Address
Bron Gondwana (editor)
Fastmail
Level 2, 2
114 William St
Melbourne VIC 3000
Australia
Email: brong@fastmailteam.com
URI: https://www.fastmail.com