IMAP Extensions: Quick Flag Changes Resynchronization (CONDSTORE) and Quick Mailbox Resynchronization (QRESYNC)
RFC 7162

Internet Engineering Task Force (IETF)                       A. Melnikov
Request for Comments: 7162                                     Isode Ltd
Obsoletes: 4551, 5162                                        D. Cridland
Updates: 2683                                               Surevine Ltd
Category: Standards Track                                       May 2014
ISSN: 2070-1721

   IMAP Extensions: Quick Flag Changes Resynchronization (CONDSTORE)
             and Quick Mailbox Resynchronization (QRESYNC)

Abstract

   Often, multiple IMAP (RFC 3501) clients need to coordinate changes to
   a common IMAP mailbox.  Examples include different clients working on
   behalf of the same user and multiple users accessing shared
   mailboxes.  These clients need a mechanism to efficiently synchronize
   state changes for messages within the mailbox.

   Initially defined in RFC 4551, the Conditional Store facility
   provides a protected update mechanism for message state information
   and a mechanism for requesting only changes to the message state.
   This memo updates that mechanism and obsoletes RFC 4551, based on
   operational experience.

   This document additionally updates another IMAP extension, Quick
   Resynchronization, which builds on the Conditional STORE extension to
   provide an IMAP client the ability to fully resynchronize a mailbox
   as part of the SELECT/EXAMINE command, without the need for
   additional server-side state or client round trips.  Hence, this memo
   obsoletes RFC 5162.

   Finally, this document also updates the line-length recommendation in
   Section 3.2.1.5 of RFC 2683.

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 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7162.

Melnikov & Cridland          Standards Track                    [Page 1]
RFC 7162                IMAP CONDSTORE & QRESYNC                May 2014

Copyright Notice

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   document authors.  All rights reserved.

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   it for publication as an RFC or to translate it into languages other
   than English.

Melnikov & Cridland          Standards Track                    [Page 2]
RFC 7162                IMAP CONDSTORE & QRESYNC                May 2014

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Requirements Notation . . . . . . . . . . . . . . . . . . . .   5
   3.  IMAP Protocol Changes . . . . . . . . . . . . . . . . . . . .   5
     3.1.  CONDSTORE Extension . . . . . . . . . . . . . . . . . . .   5
       3.1.1.  Advertising Support for CONDSTORE . . . . . . . . . .   8
       3.1.2.  New OK Untagged Responses for SELECT and EXAMINE  . .   8
       3.1.3.  STORE and UID STORE Commands  . . . . . . . . . . . .  10
       3.1.4.  FETCH and UID FETCH Commands  . . . . . . . . . . . .  16
       3.1.5.  MODSEQ Search Criterion in SEARCH . . . . . . . . . .  19
       3.1.6.  Modified SEARCH Untagged Response . . . . . . . . . .  20
       3.1.7.  HIGHESTMODSEQ Status Data Items . . . . . . . . . . .  21
       3.1.8.  CONDSTORE Parameter to SELECT and EXAMINE . . . . . .  21