7Internet Engineering Task Force (IETF) K. Murchison
8Request for Comments: 8440 B. Gondwana
9Category: Standards Track FastMail
10ISSN: 2070-1721 August 2018
13 IMAP4 Extension for Returning MYRIGHTS Information in Extended LIST
17 This document defines an extension to the Internet Message Access
18 Protocol (IMAP) LIST command that allows the client to request the
19 set of rights that the logged-in user has been granted on mailboxes,
20 along with other information typically returned by the LIST command.
24 This is an Internet Standards Track document.
26 This document is a product of the Internet Engineering Task Force
27 (IETF). It represents the consensus of the IETF community. It has
28 received public review and has been approved for publication by the
29 Internet Engineering Steering Group (IESG). Further information on
30 Internet Standards is available in Section 2 of RFC 7841.
32 Information about the current status of this document, any errata,
33 and how to provide feedback on it may be obtained at
34 https://www.rfc-editor.org/info/rfc8440.
38 Copyright (c) 2018 IETF Trust and the persons identified as the
39 document authors. All rights reserved.
41 This document is subject to BCP 78 and the IETF Trust's Legal
42 Provisions Relating to IETF Documents
43 (https://trustee.ietf.org/license-info) in effect on the date of
44 publication of this document. Please review these documents
45 carefully, as they describe your rights and restrictions with respect
46 to this document. Code Components extracted from this document must
47 include Simplified BSD License text as described in Section 4.e of
48 the Trust Legal Provisions and are provided without warranty as
49 described in the Simplified BSD License.
58Murchison & Gondwana Standards Track [Page 1]
60RFC 8440 IMAP LIST-MYRIGHTS August 2018
65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
66 2. Conventions Used in This Document . . . . . . . . . . . . . . 2
67 3. MYRIGHTS Return Option to LIST Command . . . . . . . . . . . 2
68 4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 3
69 5. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 4
70 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
71 7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 4
72 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
73 8.1. Registration of IMAP Capability LIST-MYRIGHTS . . . . . . 4
74 8.2. Registration of LIST-EXTENDED Option MYRIGHTS . . . . . . 4
75 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
76 9.1. Normative References . . . . . . . . . . . . . . . . . . 5
77 9.2. Informative References . . . . . . . . . . . . . . . . . 6
78 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6
79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
83 IMAP [RFC3501] clients typically fetch the set of rights granted on
84 mailboxes so they can expose the allowed functionality to the logged-
85 in user. In order to do that, the client is forced to issue a LIST
86 or LSUB command to list all available mailboxes, followed by a
87 MYRIGHTS command for each mailbox found. This document defines an
88 extension to the to IMAP LIST command that is identified by the
89 capability string "LIST-MYRIGHTS". The LIST-MYRIGHTS extension
90 allows the client to request the set of rights that the logged-in
91 user has been granted on mailboxes, along with other information
92 typically returned by the LIST command.
942. Conventions Used in This Document
96 In examples, "C:" indicates lines sent by a client that is connected
97 to a server. "S:" indicates lines sent by the server to the client.
99 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
100 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
101 "OPTIONAL" in this document are to be interpreted as described in
102 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
103 capitals, as shown here.
1053. MYRIGHTS Return Option to LIST Command
107 [RFC4314] defines the MYRIGHTS command, which is used by an IMAP
108 client to determine the set of rights that the logged-in user has
109 been granted on a given mailbox. Frequently, a client will have to
110 look up the rights for some or all of the mailboxes returned by the
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116RFC 8440 IMAP LIST-MYRIGHTS August 2018
119 LIST command. Doing so in multiple MYRIGHTS commands wastes
120 bandwidth and can degrade performance if the client does not pipeline
123 This document extends the LIST command with a new "MYRIGHTS" return
124 option [RFC5258] that allows the client to request all of the desired
125 information in a single command. For each listable mailbox matching
126 the list pattern and selection options, the server MUST return an
127 untagged LIST response and SHOULD also return an untagged MYRIGHTS
128 response containing the set of rights granted to the logged-in user.
129 The ordering of the responses is significant only in that the server
130 MUST NOT send a MYRIGHTS response for a given mailbox before it sends
131 the LIST response for that mailbox.
133 If the server is unable to look up the set of rights for a given
134 mailbox, it does not send the MYRIGHTS reply for that mailbox.
136 Client authors ought to note that generating the MYRIGHTS responses
137 for a large number of mailboxes may be an expensive operation for the
138 server. Clients SHOULD use a suitable match pattern and/or selection
139 option to limit the set of mailboxes returned to only those in whose
140 rights they are interested.
144 In this example, the "bar" mailbox doesn't exist, so it has no
147 C: A01 LIST "" % RETURN (MYRIGHTS)
148 S: * LIST () "." "INBOX"
149 S: * MYRIGHTS "INBOX" lrswipkxtecda
150 S: * LIST () "." "foo"
151 S: * MYRIGHTS "foo" lrs
152 S: * LIST (\NonExistent) "." "bar"
153 S: A01 OK List completed.
155 In this example, the LIST reply for the "foo" mailbox is returned
156 because it has matching children, but no MYRIGHTS reply is returned,
157 because "foo" itself doesn't match the selection criteria.
159 C: A02 LIST (SUBSCRIBED RECURSIVEMATCH) "" % RETURN (MYRIGHTS)
160 S: * LIST (\Subscribed) "." "INBOX"
161 S: * MYRIGHTS "INBOX" lrswipkxtecda
162 S: * LIST () "." "foo" (CHILDINFO ("SUBSCRIBED"))
163 S: A02 OK List completed.
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172RFC 8440 IMAP LIST-MYRIGHTS August 2018
177 The following syntax specification uses the augmented Backus-Naur
178 Form (BNF) as described in [RFC5234]. Terms not defined here are
179 taken from [RFC5258].
181 return-option =/ "MYRIGHTS"
1836. Security Considerations
185 In addition to the security considerations described in [RFC4314],
186 this extension makes it a bit easier for clients to overload the
187 server by requesting MYRIGHTS information for a large number of
188 mailboxes. However, as noted in the introduction, existing clients
189 already try to do that by generating a large number of MYRIGHTS
190 commands for each mailbox in which they are interested. While
191 performing MYRIGHTS information retrieval for big lists of mailboxes,
192 a server implementation needs to make sure that it can still serve
193 other IMAP connections and yield execution to other connections, when
1967. Privacy Considerations
198 This specification does not introduce any additional privacy concerns
199 beyond those described in [RFC4314].
2018. IANA Considerations
2038.1. Registration of IMAP Capability LIST-MYRIGHTS
205 This document defines the "LIST-MYRIGHTS" IMAP capability that has
206 been added to the "IMAP Capabilities" registry [CAPABILITIES].
2088.2. Registration of LIST-EXTENDED Option MYRIGHTS
210 This section registers the "MYRIGHTS" option that has been added to
211 the "LIST-EXTENDED options" registry [EXTENDED].
213 LIST-EXTENDED option name: MYRIGHTS
215 LIST-EXTENDED option type: RETURN
217 LIST-EXTENDED option description: Causes the LIST command to return
218 MYRIGHTS responses in addition to LIST responses.
220 Published specification: RFC 8440, Section 3
222 Security considerations: RFC 8440, Section 6
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228RFC 8440 IMAP LIST-MYRIGHTS August 2018
231 Intended usage: COMMON
233 Person and email address to contact for further information:
234 Kenneth Murchison <murch@fastmailteam.com>
236 Owner/Change controller: IESG <iesg@ietf.org>
2409.1. Normative References
243 IANA, "Internet Message Access Protocol (IMAP)
244 Capabilities Registry", <https://www.iana.org/assignments/
245 imap-capabilities/imap-capabilities>.
248 IANA, "Internet Message Access Protocol (IMAP) LIST
250 <https://www.iana.org/assignments/imap-list-extended>.
252 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
253 Requirement Levels", BCP 14, RFC 2119,
254 DOI 10.17487/RFC2119, March 1997,
255 <https://www.rfc-editor.org/info/rfc2119>.
257 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
258 4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003,
259 <https://www.rfc-editor.org/info/rfc3501>.
261 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension",
262 RFC 4314, DOI 10.17487/RFC4314, December 2005,
263 <https://www.rfc-editor.org/info/rfc4314>.
265 [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
266 Specifications: ABNF", STD 68, RFC 5234,
267 DOI 10.17487/RFC5234, January 2008,
268 <https://www.rfc-editor.org/info/rfc5234>.
270 [RFC5258] Leiba, B. and A. Melnikov, "Internet Message Access
271 Protocol version 4 - LIST Command Extensions", RFC 5258,
272 DOI 10.17487/RFC5258, June 2008,
273 <https://www.rfc-editor.org/info/rfc5258>.
275 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
276 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
277 May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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284RFC 8440 IMAP LIST-MYRIGHTS August 2018
2879.2. Informative References
289 [RFC5819] Melnikov, A. and T. Sirainen, "IMAP4 Extension for
290 Returning STATUS Information in Extended LIST", RFC 5819,
291 DOI 10.17487/RFC5819, March 2010,
292 <https://www.rfc-editor.org/info/rfc5819>.
296 This document is based largely on [RFC5819]. The authors would like
297 to thank the authors of that document for providing both inspiration
298 and some borrowed text for this document. The authors would also
299 like to thank Barry Leiba for contributing his ideas and support for
300 writing this specification.
306 Level 2, 114 William Street
310 Email: murch@fastmailteam.com
315 Level 2, 114 William Street
319 Email: brong@fastmailteam.com
338Murchison & Gondwana Standards Track [Page 6]