The Internet Email to Support Diverse Service Environments (Lemonade) Profile
RFC 5550

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Network Working Group                                   D. Cridland, Ed.
Request for Comments: 5550                              A. Melnikov, Ed.
Obsoletes: 4550                                            Isode Limited
Updates: 4469, 4467                                         S. Maes, Ed.
Category: Standards Track                                         Oracle
                                                             August 2009

                         The Internet Email to
        Support Diverse Service Environments (Lemonade) Profile

Abstract

   This document describes a profile (a set of required extensions,
   restrictions, and usage modes), dubbed Lemonade, of the IMAP, mail
   submission, and Sieve protocols.  This profile allows clients
   (especially those that are constrained in memory, bandwidth,
   processing power, or other areas) to efficiently use IMAP and
   Submission to access and submit mail.  This includes the ability to
   forward received mail without needing to download and upload the
   mail, to optimize submission, and to efficiently resynchronize in
   case of loss of connectivity with the server.

   The Lemonade Profile relies upon several extensions to IMAP, Sieve,
   and Mail Submission protocols.  The document also defines a new IMAP
   extension and registers several new IMAP keywords.

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (c) 2009 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 in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

Cridland, et al.            Standards Track                     [Page 1]
RFC 5550                    Lemonade Profile                 August 2009

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Introduction ....................................................3
   2. Conventions Used in This Document ...............................4
   3. Summary of the Required Support .................................4
      3.1. Lemonade Submission Servers ................................4
      3.2. Lemonade Message Stores ....................................5
      3.3. Lemonade Message Delivery Agents ...........................7
   4. Lemonade Submission Servers .....................................7
      4.1. Forward without Download ...................................7
      4.2. Pipelining .................................................8
      4.3. DSN Support ................................................8
      4.4. Message Size Declaration ...................................8
      4.5. Enhanced Status Code Support ...............................8
      4.6. Encryption and Compression .................................8
   5. Lemonade Message Stores .........................................9
      5.1. Quick Resynchronization ....................................9
      5.2. Message Part Handling ......................................9
      5.3. Compression ...............................................10
      5.4. Notifications .............................................10
      5.5. Searching and View Filters ................................12
      5.6. Mailbox Handling ..........................................12
      5.7. Forward without Download ..................................12
      5.8. Additional IMAP Extensions ................................13
      5.9. Registration of $Forwarded IMAP Keyword ...................13
      5.10. Registration of $SubmitPending and $Submitted
            IMAP Keywords ............................................13
      5.11. Related IMAP Extensions ..................................14
   6. Lemonade Message Delivery Agents ...............................14