IMAP4 Multimailbox SEARCH Extension
RFC 6237

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• IESG evaluation record
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• Email expansions
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• 07

Internet Engineering Task Force (IETF)                          B. Leiba
Request for Comments: 6237                           Huawei Technologies
Updates: 4466                                                A. Melnikov
Category: Experimental                                     Isode Limited
ISSN: 2070-1721                                                 May 2011

                  IMAP4 Multimailbox SEARCH Extension

Abstract

   The IMAP4 specification allows the searching of only the selected
   mailbox.  A user often wants to search multiple mailboxes, and a
   client that wishes to support this must issue a series of SELECT and
   SEARCH commands, waiting for each to complete before moving on to the
   next.  This extension allows a client to search multiple mailboxes
   with one command, limiting the round trips and waiting for various
   searches to complete, and not requiring disruption of the currently
   selected mailbox.  This extension also uses MAILBOX and TAG fields in
   ESEARCH responses, allowing a client to pipeline the searches if it
   chooses.  This document updates RFC 4466.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for examination, experimental implementation, and
   evaluation.

   This document defines an Experimental Protocol for the Internet
   community.  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).  Not
   all documents approved by the IESG are a candidate for any level of
   Internet Standard; see 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/rfc6237.

Leiba & Melnikov              Experimental                      [Page 1]
RFC 6237           IMAP4 Multimailbox SEARCH Extension          May 2011

Copyright Notice

   Copyright (c) 2011 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
   (http://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
      1.1. Conventions Used in This Document ..........................3
   2. New ESEARCH Command .............................................3
      2.1. The ESEARCH Response .......................................4
      2.2. Source Options: Specifying Mailboxes to Search .............5
   3. Examples ........................................................6
   4. Formal Syntax ...................................................7
   5. Security Considerations .........................................8
   6. IANA Considerations .............................................9
   7. Acknowledgements ................................................9
   8. Normative References ............................................9

1.  Introduction

   The IMAP4 specification allows the searching of only the selected
   mailbox.  A user often wants to search multiple mailboxes, and a
   client that wishes to support this must issue a series of SELECT and
   SEARCH commands, waiting for each to complete before moving on to the
   next.  The commands can't be pipelined, because the server might run
   them in parallel, and the untagged SEARCH responses could not then be
   distinguished from each other.

   This extension allows a client to search multiple mailboxes with one
   command, and includes MAILBOX and TAG fields in the ESEARCH response,
   yielding the following advantages:

   o  A single command limits the number of round trips needed to search
      a set of mailboxes.

   o  A single command eliminates the need to wait for one search to
      complete before starting the next.

Leiba & Melnikov              Experimental                      [Page 2]
RFC 6237           IMAP4 Multimailbox SEARCH Extension          May 2011

   o  A single command allows the server to optimize the search, if it
      can.

   o  A command that is not dependent upon the selected mailbox
      eliminates the need to disrupt the selection state or to open
      another IMAP connection.

   o  The MAILBOX, UIDVALIDITY, and TAG fields in the responses allow a
      client to distinguish which responses go with which search (and