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                          <Lemonade Profile>              October 2005


Lemonade
Internet Draft: Lemonade Profile                             S. H. Maes
Document: draft-ietf-lemonade-profile-05.txt                A. Melnikov
Expires: April 2006                                        October 2005


                             Lemonade Profile

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
        http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
        http://www.ietf.org/shadow.html.

Abstract

   This document describes a profile (a set of required extensions,
   restrictions and usage modes) of the IMAP and mail submission
   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 extensions to IMAP and Mail
   Submission protocols; specifically URLAUTH and CATENATE IMAP protocol
   [RFC3501] extensions and BURL extension to the SUBMIT protocol
   [RFC2476].




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Conventions used in this document

   In examples, "M:", "I:" and "S:" indicate lines sent by the client
   messaging user agent, IMAP e-mail server and SMTP submit server
   respectively.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].


Table of Contents

   Status of this Memo...............................................1
   Abstract..........................................................1
   Conventions used in this document.................................2
   Table of Contents.................................................2
   1. Introduction...................................................3
   2. Forward without download.......................................3
      2.1. Motivations...............................................3
      2.2. Message Sending Overview..................................3
      2.3. Traditional Strategy......................................4
      2.4. Step by step description..................................5
      2.5. Normative statements related to forward without download..9
      2.6. Security Considerations for pawn-tickets..................9
      2.7. The fcc problem...........................................9
   3. Message Submission............................................10
      3.1. Pipelining...............................................10
      3.2. DSN Support..............................................10
      3.3. Message size declaration.................................10
      3.4. Enhanced status code Support.............................10
      3.5. TLS......................................................11
   4. Quick resynchronization.......................................11
   5. Additional IMAP extensions....................................11
   6. Summary of IMAP and SMTP extensions required for
        Lemonade profile............................................11
   7. Future work...................................................12
   8. Security Considerations.......................................12
      8.1. Confidentiality Protection of Submitted Messages.........12
      8.2. TLS......................................................13
   9. IANA Considerations...........................................13
   10. References...................................................13
      10.1. Normative References....................................13
      10.2. Informative References..................................15
   Open issues......................................................15
   Version History..................................................15
   Acknowledgments..................................................16
   Authors Addresses................................................17
   Intellectual Property Statement..................................17


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1.
   Introduction

   Lemonade provides enhancements to Internet email to support diverse
   service environments.

   This document describes the lemonade profile that includes:
      - "Forward without download" that describes exchanges between
        Lemonade clients and servers to allow to submit new email
        messages incorporating content which resides on locations
        external to the client.
      - Quick mailbox resynchronization using [CONDSTORE].

   The organization of this document is as follows.  Section 2 describes
   the Forward without download. Section 3 describes additional SMTP
   extensions that must be supported by all Lemonade Submission servers.
   Section 4 describes IMAP quick resynchronization.

2.
  Forward without download

2.1.
    Motivations

   The advent of client/server email using the [RFC3501], [RFC2821] and
   [RFC2476] protocols has changed what formerly were local disk
   operations to become excessive and repetitive network data
   transmissions.

   Lemonade "forward without download" makes use of the [BURL] SUBMIT
   extension to enable access to external sources during the submission
   of a message.  In combination with the IMAP [URLAUTH] extension,
   inclusion of message parts or even entire messages from the IMAP mail
   store is possible with a minimal trust relationship between the IMAP
   and SMTP SUBMIT servers.

   Lemonade "forward without download" has the advantage of maintaining
   one submission protocol, and thus avoids the risk of having multiple
   parallel and possible divergent mechanisms for submission. The
   client can use Submit/SMTP [RFC2476] extensions without these being
   added to IMAP. Furthermore, by keeping the details of message
   submission in the SMTP SUBMIT server, Lemonade "forward without
   download" can work with other message retrieval protocols such as
   POP, NNTP, or whatever else may be designed in the future.

2.2.
    Message Sending Overview

   The act of sending an email message can be thought of as involving
   multiple steps: initiation of a new draft, draft editing, message
   assembly, and message submission.


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   Initiation of a new draft and draft editing takes place on the MUA.
   Frequently, users choose to save more complex messages on an
   [RFC3501] server (via the APPEND command with the \Draft flag) for
   later recall by the MUA and resumption of the editing process.

   Message assembly is the process of producing a complete message from
   the final revision of the draft and external sources.  At assembly
   time, external data is retrieved and inserted in the message.

   Message submission is the process of inserting the assembled message
   into the [RFC2821] infrastructure, typically using the [RFC2476]
   protocol.

2.3.
    Traditional Strategy

   Traditionally, messages are initiated, edited, and assembled entirely
   within an MUA, although drafts may be saved to an [RFC3501] server
   and later retrieved from the server.  The completed text is then
   transmitted to an MSA for delivery.

   There is often no clear boundary between the editing and assembly
   process.  If a message is forwarded, its content is often retrieved
   immediately and inserted into the message text.  Similarly, when
   external content is inserted or attached, the content is usually
   retrieved immediately and made part of the draft.

   As a consequence, each save of a draft and subsequent retrieve of the
   draft transmits that entire (possibly large) content, as does message
   submission.

   In the past, this was not much of a problem, because drafts, external
   data, and the message submission mechanism were typically located on
   the same system as the MUA.  The most common problem was running out
   of disk quota.
















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2.4.
    Step by step description

   The model distinguishes between a Messaging User Agent (MUA), an
   IMAPv4Rev1 Server ([RFC3501]) and a SMTP submit server ([RFC2476]),
   as illustrated in Figure 1.

        +--------------------+               +--------------+
        |                    | <------------ |              |
        |     MUA (M)        |               | IMAPv4 Rev1  |
        |                    |               |  Server      |
        |                    | ------------> | (Server I)   |
        +--------------------+               +--------------+
               ^  |                             ^     |
               |  |                             |     |
               |  |                             |     |
               |  |                             |     |
               |  |                             |     |
               |  |                             |     |
               |  |                             |     v
               |  |                          +--------------+
               |  |------------------------->|   SMTP       |
               |                             |   Submit     |
               |-----------------------------|   Server     |
                                             |  (Server S)  |
                                             +--------------+
             Figure 1: Lemonade "forward without download"


   Lemonade "forward without download" allows a Messaging User Agent to
   compose and forward an e-mail combining fragments that are located in
   an IMAP server, without having to download these fragments to the
   server.

   In the [BURL]/[CATENATE] variant of the Lemonade "forward without
   download" strategy, messages are initially composed and edited within
   an MUA.  The [CATENATE] extension to [RFC3501] is then used to create
   the messages on the IMAP server by transmitting new text and
   assembling them. [ UIDPLUS extension"">UIDPLUS] IMAP extension is used by the client in
   order to learn the UID of the created messages. Finally a [URLAUTH]


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   format URL is given to a [RFC2476] server for submission using the
   [BURL] extension.

   The flow involved to support such a use case consists of:
      M: {to I -- Optional} The client connects to the IMAP server,
     optionally starts TLS (if data confidentiality is required),
     authenticates, opens a mailbox ("INBOX" in the example below) and
     fetches body structures (See [RFC3501]).

     Example:
           M: A0051 UID FETCH 25627 (UID BODYSTRUCTURE)
           I: * 161 FETCH (UID 25627 BODYSTRUCTURE (("TEXT" "PLAIN"
              ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 23)(
              "TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME"
              "trip.txt")
              "<960723163407.20117h@washington.example.net>"
              "Your trip details" "BASE64" 4554 73) "MIXED"))
           I: A0051 OK completed

      M: {to I} The client invokes CATENATE (See [CATENATE] for details
     of the semantics and steps) - this allows the MUA to create
     messages on the IMAP using new data combined with one or more
     message part already present on the IMAP server.


        M: A0052 APPEND Sent FLAGS (\Seen $MDNSent)
           CATENATE (TEXT {738}
        I: + Ready for literal data
        M: Return-Path: <bar@example.org>
        M: Received: from [127.0.0.2]
        M:           by rufus.example.org via TCP (internal)
        M:           with ESMTPA;
        M:           Thu, 11 Nov 2004 16:57:07 +0000
        M: Message-ID: <419399E1.6000505@example.org>
        M: Date: Thu, 12 Nov 2004 16:57:05 +0000
        M: From: Bob Ar <bar@example.org>
        M: X-Accept-Language: en-us, en
        M: MIME-Version: 1.0
        M: To: foo@example.net
        M: Subject: About our holiday trip
        M: Content-Type: multipart/mixed;
        M:               boundary="------------030308070208000400050907"
        M:
        M: --------------030308070208000400050907
        M: Content-Type: text/plain; charset=us-ascii; format=flowed
        M: Content-Transfer-Encoding: 7bit
        M:
        M: Our travel agent has sent the updated schedule.
        M:


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        M: Cheers,
        M: Bob
        M: --------------030308070208000400050907
        M:  URL "/INBOX;UIDVALIDITY=385759045/;
           UID=25627;Section=2.MIME" URL "/INBOX;
           UIDVALIDITY=385759045/;UID=25627;Section=2" TEXT {44}
        I: + Ready for literal data
        M:
        M: --------------030308070208000400050907--
        M: )
        I: A0052 OK [APPENDUID 387899045 45] CATENATE Completed

      M: {to I} The client uses GENURLAUTH command to request a URLAUTH
     URL (See [URLAUTH]).
      I: {to M} The IMAP server returns a URLAUTH URL suitable for later
     retrieval with URLFETCH (See [URLAUTH] for details of the semantics
     and steps).

        M: A0054 GENURLAUTH "imap://bob.ar@example.org/Sent;
           UIDVALIDITY=387899045/;uid=45/;expire=2005-10-
           28T23:59:59Z;urlauth=submit+bob.ar" INTERNAL
        I: * GENURLAUTH "imap://bob.ar@example.org/Sent;
           UIDVALIDITY=387899045/;uid=45/;expire=
           2005-10-28T23:59:59Z;urlauth=submit+bob.ar:
           internal:91354a473744909de610943775f92038"
        I: A0054 OK GENURLAUTH completed

      M: {to S} The client connects to the mail submission server and
     starts a new mail transaction. It uses BURL to let the SMTP submit
     server fetch the content of the message from the IMAP server (See
     [BURL] for details of the semantics and steps - this allows the MUA
     to authorize the SMTP submit server to access the message composed
     as a result of the CATENATE step).

        M: EHLO potter.example.org
        S: 250-owlry.example.com
        S: 250-8BITMIME
        S: 250-BINARYMIME
        S: 250-PIPELINING
        S: 250-BURL imap
        S: 250-CHUNKING
        S: 250-AUTH PLAIN
        S: 250-DSN
        S: 250-SIZE 10240000
        S: 250-STARTTLS
        S: 250 ENHANCEDSTATUSCODES
     <<STARTTLS>>
        M: AUTH PLAIN aGFycnkAaGFycnkAYWNjaW8=
        S: 235 2.7.0 PLAIN authentication successful.


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        M: MAIL FROM:<bob.ar@example.org>
        S: 250 2.5.0 Address Ok.
        M: RCPT TO:<foo@example.net>
        S: 250 2.1.5 foo@example.net OK.
        M: BURL imap://bob.ar@example.org/Sent;UIDVALIDITY=387899045/;
           uid=45/;urlauth=submit+bar:internal:
           91354a473744909de610943775f92038 LAST

      S: {to I} The mail submission server uses URLFETCH to fetch the
     message to be sent (See [URLAUTH] for details of the semantics and
     steps. The so-called "pawn-ticket" authorization mechanism uses a
     URI which contains its own authorization credentials.).
      I: {to S} Provides the message composed as a result of the
     CATENATE step).

     Mail submission server opens IMAP connection to the IMAP server:

        I: * OK [CAPABILITY IMAP4REV1 STARTTLS NAMESPACE LITERAL+
           CATENATE URLAUTH] imap.example.com
           IMAP server ready
        S: a001 LOGIN submitserver secret
        I: a001 OK submitserver logged in
        S: a002 URLFETCH "imap://bob.ar@example.org/Sent;
           UIDVALIDITY=387899045/;uid=45/;urlauth=submit+bob.ar:
           internal:91354a473744909de610943775f92038"
        I: * URLFETCH "imap://bob.ar@example.org/Sent;
           UIDVALIDITY=387899045/;uid=45/;urlauth=submit+bob.ar:
           internal:91354a473744909de610943775f92038" {15065}
        ...message body follows...
        S: a002 OK URLFETCH completed
        I: a003 LOGOUT
        S: * BYE See you later
        S: a003 OK Logout successful

     Note that if the IMAP server doesn’t send CAPABILITY response code
     in the greeting, the mail submission server must issue the
     CAPABILITY command to learn about supported IMAP extensions as
     described in RFC 3501.

     Also, if data confidentiality is required the mail submission
     server should start TLS before issuing the LOGIN command.

     S2: {to M} OK (2XX)

     Submission server returns OK to the MUA:
        S: 250 2.5.0 Ok.

     M: {to I} The client marks the forwarded message on the IMAP
     server.


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        M: A0053 UID STORE 25627 +FLAGS.SILENT ($Forwarded)
        I: A0053 OK STORE completed

     Note: the UID STORE command shown above will only work if the
     marked message is in the currently selected mailbox. This command
     can be omitted.


2.5.
    Normative statements related to forward without download

   Lemonade compliant IMAP servers MUST support IMAPv4 Rev1 [RFC3501],
   CATENATE [CATENATE], UIDPLUS [ UIDPLUS extension"">UIDPLUS] and URLAUTH [URLAUTH]. This
   support MUST be declared via CAPABILITY [RFC3501].

   Lemonade compliant submit servers MUST support the BURL [BURL],
   8BITMIME [8BITMIME], BINARYMIME [CHUNKING] and CHUNKING [CHUNKING].
   This support MUST be declared via EHLO [RFC2821].
   Note that supporting both CHUNKING and BURL allows clients to create
   a new message containing all or part of a previously-received message
   without needing to first compose a new message using CATENATE.

   Additional normative statements are provided in other sections.


2.6.
    Security Considerations for pawn-tickets.

   The so-called "pawn-ticket" authorization mechanism uses a URI, which
   contains its own authorization credentials using [URLAUTH].  The
   advantage of this mechanism is that the SMTP submit [RFC2476] server
   cannot access any data on the [RFC3501] server without a "pawn-
   ticket" created by the client.

   The "pawn-ticket" grants access only to the specific data that the
   SMTP submit [RFC2476] server is authorized to access, can be revoked
   by the client, and can have a time-limited validity.


2.7.
    The fcc problem

   The "fcc problem" refers to delivering a copy of a message to a
   "file carbon copy" recipient.  By far, the most common case of fcc is
   a client leaving a copy of outgoing mail in a "sent messages" or
   "outbox" mailbox.

   In the traditional strategy, the MUA duplicates the effort spent in
   transmitting to the MSA by writing the message to the fcc destination
   in a separate step.  This may be a write to a local disk file or an
   APPEND to a mailbox on an IMAP server.  The latter is one of the


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   "excessive and repetitive network data transmissions" which
   represents the "problem" aspect of the "fcc problem".

   The [CATENATE] extension to [RFC3501] addresses the fcc problem.  It
   requires making several simplifying assumptions:
       (1a) there is one, and only one, fcc destination on a single
   server
       (2a) the server which holds the fcc is the same as the server
   which stages the outgoing message for submission


3.
  Message Submission

   LEMONADE compliant mail submission servers are expected to implement
   the following set of SMTP extensions to make message submission
   efficient.

   Lemonade clients SHOULD take advantage of these features.


3.1.
    Pipelining

   Mobile clients regularly use networks with a relatively high latency.
   Avoidance of round-trips within a transaction has a great advantage
   for the reduction in both bandwidth and total transaction time.
   For this reason LEMONADE compliant mail submission servers MUST
   support the SMTP Service Extensions for Command Pipelining [REF2197].

   Clients SHOULD pipeline.


3.2.
    DSN Support

   LEMONADE compliant mail submission servers MUST support SMTP service
   extensions for delivery status notifications [RFC3461].


3.3.
    Message size declaration

   LEMONADE compliant mail submission servers MUST support the SMTP
   Service Extension for Message Size Declaration [RFC2927].

   Note a LEMONADE compliant mail submission server must perform message
   size limit enforcement after performing expansion of all BURL parts.


3.4.
    Enhanced status code Support





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   LEMONADE compliant mail submission servers MUST support SMTP Service
   Extension for Returning Enhanced Error Codes [RFC2034].

3.5.
    TLS

   LEMONADE Compliant mail submission servers MUST support SMTP Service
   Extension for Secure SMTP over TLS [RFC2487].


4.
  Quick resynchronization

   LEMONADE Compliant IMAP servers MUST support the CONDSTORE
   [CONDSTORE] extension. It allows a client to quickly resynchronize
   any mailbox by asking the server to return all flag changes that has
   occurred since the last known mailbox synchronization mark.

   [IMAP-DISC] shows how to perform quick mailbox resynchronization.


5.
  Additional IMAP extensions

   Lemonade compliant IMAP servers MUST support the NAMESPACE
   [NAMESPACE] extension.

   Lemonade compliant IMAP servers MUST support the LITERAL+ [LITERAL+]
   extension. The extension allows clients to save a round trip each
   time a non-synchronizing literal is sent.

   LEMONADE Compliant IMAP servers MUST support IMAP over TLS [RFC3501]
   as required by RFC 3501.


6.
  Summary of IMAP and SMTP extensions required for Lemonade profile

               ------------------------------------------------------___
               |Name of an SMTP extension|         Comment          |
               |-------------------------|--------------------------|
               |        PIPELINING       |       Section 3.1        |
               |-------------------------|--------------------------|
               |           DNS           |       Section 3.2        |

               |-------------------------|--------------------------|
               |           SIZE          |       Section 3.3        |
               |-------------------------|--------------------------|
               |  ENHANCEDSTATUSCODES    |       Section 3.4        |
               |-------------------------|--------------------------|
               |        STARTTLS         |       Section 3.5        |
               |-------------------------|--------------------------|
               |           BURL          | Forward without download,|
               |                         |         Section 2        |


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               |-------------------------|--------------------------|
               |        CHUNKING,        |       Section 2.5        |
               |       BINARYMIME        |       Section 2.5        |
               |-------------------------|--------------------------|
               |        8BITMIME,        |    Required by BURL      |
               |-------------------------|--------------------------|

               ------------------------------------------------------___
               |Name of an IMAP extension|         Comment          |
               |-------------------------|--------------------------|
               |        NAMESPACE        |       Section 5          |
               |-------------------------|--------------------------|
               |        CONDSTORE        |       Section 4          |
               |-------------------------|--------------------------|
               |        STARTTLS         |Required by IMAP (RFC3501)|
               |-------------------------|--------------------------|
               |        URLAUTH,         | Forward without download,|
               |        CATENATE,        |    Section 2             |
               |        UIDPLUS          |                          |
               |-------------------------|--------------------------|
               |        LITERAL+         |       Section 5          |
               |-------------------------|--------------------------|


7.
  Future work

   Future phases of the Lemonade profile are expected to address issues
   related to access of email from mobile devices, possibly including:
      - Media conversion (static and possibly streamed)
      - Transport optimization for low or costly bandwidth and less
        reliable mobile networks (e.g. quick reconnect)
      - Server to client notifications, possibly outside of the

        traditional IMAP band
      - Dealing with firewall and intermediaries
      - Compression and other bandwidth optimization
      - Filtering
      - Other considerations for mobile clients

8.
  Security Considerations

   Security considerations on Lemonade "forward without download" are
   discussed throughout section 2. Additional security considerations
   can be found in [RFC3501] and other documents describing other SMTP
   and IMAP extensions comprising Lemonade Profile.


8.1.
    Confidentiality Protection of Submitted Messages




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   When clients submit new messages, link protection such as TLS guards
   against an eavesdropper seeing the contents of the submitted message.
   It's worth noting, however, that even if TLS is not used, the
   security risks are no worse if BURL is used to reference the text
   than if the text is submitted directly.  If BURL is not used, an
   eavesdropper gains access to the full text of the message.  If BURL
   is used, the eavesdropper may or may not be able to gain such access,
   depending on the form of BURL used.  For example, some forms restrict
   use of the URL to an entity authorized as a submission server or a
   specific user.

8.2.
    TLS

   When LEMONADE clients uses the BURL extension to mail Submission, an
   extension that requires sending a URLAUTH token to the mail
   submission server, such a token should be protected from interception
   to avoid a replay attack that will disclose the contents of the
   message to an attacker. TLS based encryption of the mail submission
   path will provide protection against this attack.

   LEMONADE clients SHOULD use TLS protected IMAP and mail submission
   channels when using BURL-based message submission to protect the

   URLAUTH token from interception.

   LEMONADE Compliant mail submission server SHOULD use TLS protected
   IMAP connection when fetching message content using the URLAUTH token
   provided by the LEMONADE client.

   When a client uses SMTP STARTTLS to send a BURL command which
   references non-public information there is a user expectation that
   the entire message content will be treated confidentially.  To
   address this expectation, the message submission server should use
   STARTTLS or a mechanism providing equivalent data confidentiality
   when fetching the content referenced by that URL.


9.
  IANA Considerations

   This document doesn't require any IANA registration or action.


10.
   References

10.1.
     Normative References

   [BURL]    Newman, C. "Message Composition", draft-ietf-lemonade-burl-
      XX.txt (work in progress).




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   [8BITMIME]   Klensin, J., Freed, N., Rose, M., Stefferud, E., and D.
      Crocker, "SMTP Service Extension for 8bit-MIMEtransport", RFC
      1652, July 1994.

   [CHUNKING]  Vaudreuil, G., "SMTP Service Extensions for Transmission
      of Large and Binary MIME Messages", RFC 3030, December 2000.

   [CATENATE] Resnick, P. "Internet Message Access Protocol (IMAP)
      CATENATE Extension", draft-ietf-lemonade-catenate-XX, (work in
      progress).

   [UIDPLUS] Crispin, M., "Internet Message Access Protocol (IMAP) -

      UIDPLUS extension", work in progress, draft-crispin-imap-
      rfc2359bis-XX.txt.

   [RFC2119] Brader, S.  "Keywords for use in RFCs to Indicate
      Requirement Levels", RFC 2119, March 1997.
      http://www.ietf.org/rfc/rfc2119

   [RFC2197] Freed, N. "SMTP Service Extension for Command Pipelining",
      RFC 2197, September 1997. http://www.ietf.org/rfc/rfc2197

   [RFC2476] Gellens, R. and Klensin, J., "Message Submission", RFC
      2476, December 1998. http://www.ietf.org/rfc/rfc2476

   [RFC2487] Hoffman, P. "SMTP Service Extension for Secure SMTP over
      TLS ", RFC 2487, Jan 1999.  http://www.ietf.org/rfc/rfc2487

   [RFC2821]  Klensin, J., "Simple Mail Transfer Protocol", RFC 2821,
      April 2001.

   [RFC3501] Crispin, M. "IMAP4, Internet Message Access Protocol
      Version 4 rev1", RFC 3501, March 2003.
      http://www.ietf.org/rfc/rfc3501

   [RFC3461] Moore, K., "Simple Mail Transfer Protocol (SMTP) Service
      Extension for Delivery Status Notifications (DSNs)", RFC 3461,
      January 2003. http://www.ietf.org/rfc/rfc3461

   [URLAUTH] Crispin, M. and Newman, C., "Internet Message Access
      Protocol (IMAP) - URLAUTH Extension", draft-ietf-lemonade-urlauth-
      XX.txt, (work in progress).

   [RFC2034] Freed, N., "SMTP Service Extension for Returning Enhanced
      Error Codes", RFC 2034, October 1996.

   [NAMESPACE] Gahrns, M. and C. Newman, "IMAP4 Namespace", RFC 2342,
   May 1998.



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                          <Lemonade Profile>              October 2005


   [SMTPAUTH] Myers, J., "SMTP Service Extension for Authentication",
   RFC 2554, March 1999.

   [LITERAL+] Myers, J., "IMAP4 non-synchronizing literals", RFC 2088,
   January 1997.

   [CONDSTORE] Melnikov, A. and S. Hole, "IMAP Extension for Conditional
      STORE", work in progress.


10.2.
     Informative References

   [IMAP-DISC] Melnikov, A.  "Synchronization Operations For
      Disconnected Imap4 Clients", IMAP-DISC, work in progress,  draft-
      melnikov-imap-disc-XX.txt


Open issues

   This section will be deleted before publication.

   [1] Add some text about authentication?
   [2] Add example(s) showing use of LITERAL+.
   [3] Address the remaining comments from Dave Cridland.


Version History

   This section will be deleted before publication.

   Version 05:
   [1] Removed any references to POSTADDRESS and quick reconnect.
   [2] Added reference to LITERAL+.
   [3] Added a new section about CONDSTORE.
   [4] Split TLS text between 3 sections.
   [5] Added new text that security of BURL is no worse than sending in
   the clear.
   [6] Added ";expire" to the URLAUTHs in the forward without download
   example.

   Version 04:
   [1] Removed future delivery from the phase 1 of the profile.
   [2] Updated the list of required SMTP and IMAP extensions and
   associated normative statements.
   [3] Updated the references.
   [4] Moved (and updated) text about TLS to the Security Considerations
   section.
   [5] Removed most editor’s notes.



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                          <Lemonade Profile>              October 2005


   [6] Proposed terminology Lemonade profile phase 1 (and later phases)
   to distinguish current status from future work.

   Version 03:
   [1] Updated boilerplate.
   [2] Addressed most of the comments raised by Randy Gellens and some
   from Pete Resnick.
   [3] Purged and updated references.
   [4] Updated examples as per changes in CATENATE and other documents.
   [5] Replaced Lemonade Pull model by Lemonade "forward without
   download".
   [6] Qualified normative statement on future delivery.

   Version 02:
   [1] Improved abstract based on review comments as well as change to
   reflect the re-organized content of the present Lemonade profile.
   [2] Editorial improvement of section 2.1
   [3] Addition of section 2.5 with normative statements for lemonade
   compliant clients and servers regarding forward without download.
   [4] Addition of section 3 on message submission.
   [5] Move of media conversion to future work
   [6] Add section 4.1 on normative statements related to quick
   reconnect scheme.
   [6] Addition of Binary and 8-bit MIME Transport to future work.
   [7] Addition of IANA statement.
   [8] Update and fix of the references.


   Version 01:
   [1] We removed the sections of the profile related to mobile e-mail
      as well as discussion. This will be part of the next version of
      the Lemonade profile work.
   [2] We added detailed examples for the different steps included in
      section 2.4.
   [3] We added section 3 on media conversion.
   [4] We added examples on Quick reconnect schemes in section 4.
   [5] We updated the security considerations.
   [6] We fixed references based on updates above.
   [7] We added a future work section.
   [8] We fixed the boiler plate statements on the "status of this memo"
      and "Copyright".

Acknowledgments

   This document is a product of Lemonade WG. The editors’ thanks the
   Lemonade WG members that contributed comments and corrections, in
   particular: Randy Gellens and Dave Cridland.




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                          <Lemonade Profile>              October 2005


   This document borrows some text from draft-crispin-lemonade-pull-
   xx.txt as well as the trio [BURL], [CATENATE] and [URLAUTH].


Authors Addresses

   Stephane H. Maes
   Oracle Corporation
   500 Oracle Parkway
   M/S 4op634
   Redwood Shores, CA 94065
   USA
   Phone: +1-650-607-6296
   Email: stephane.maes@oracle.com

   Alexey Melnikov
   Isode Limited
   5 Castle Business Village
   36 Station Road
   Hampton, Middlesex
   TW12 2BX
   UK
   Email: Alexey.melnikov@isode.com

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                          <Lemonade Profile>              October 2005


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