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Versions: (draft-karp-morg-sortdisplay) 00 01 02 03 RFC 5957

Message Organization Working Group                               D. Karp
Internet-Draft                                                    Zimbra
Updates: 5256 (if approved)                             October 18, 2009
Intended status: Standards Track
Expires: April 21, 2010


       Display-based Address Sorting for the IMAP4 SORT Extension
                     draft-ietf-morg-sortdisplay-02

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on April 21, 2010.

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
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   Please review these documents carefully, as they describe your rights
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Abstract

   This document describes an IMAP protocol extension enabling server-
   side message sorting based on the commonly-displayed portion of the



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   From and To header fields.


Table of Contents

   1.  Conventions Used in This Document . . . . . . . . . . . . . . . 3
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  DISPLAY Sort Value for an Address . . . . . . . . . . . . . . . 3
   4.  The DISPLAYFROM and DISPLAYTO Sort Keys . . . . . . . . . . . . 4
   5.  Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   7.  Internationalization Considerations . . . . . . . . . . . . . . 4
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   9.  Normative References  . . . . . . . . . . . . . . . . . . . . . 5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 5




































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1.  Conventions Used in This Document

   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].


2.  Introduction

   The [SORT] extension to the [IMAP] protocol provides a means for
   server-based sorting of messages.  It defines a set of sort criteria
   and the mechanism for determining the sort value of a message for
   each such ordering.

   The [SORT] extension's FROM ordering sorts messages lexically on the
   [IMAP] addr-mailbox of the first mailbox in the From header.
   Likewise, its TO ordering sorts on the [IMAP] addr-mailbox of the
   first address in the message's To header.  This document provides two
   alternate orderings, DISPLAYFROM and DISPLAYTO, which sort messages
   lexically based on the first From or To address's [IMAP] addr-name
   (generally the same as its [RFC5322] display-name), when present.

   A server that supports the full [SORT] extension as well as the
   DISPLAYFROM and DISPLAYTO sort criteria indicates this by returning
   "SORT=DISPLAY" in its CAPABILITY response.


3.  DISPLAY Sort Value for an Address

   For the purposes of the sort keys defined in this document, the sort
   value for an [IMAP] address structure is defined as follows:

   o  If the address structure's [IMAP] addr-name is non-NIL, decode any
      [RFC2047] encoded-words.  If the resulting string is not the empty
      string, use it as the sort value for the address.

   o  Otherwise, if the address structure's [IMAP] addr-mailbox and
      [IMAP] addr-host are both non-NIL, the sort value for the address
      is addr-mailbox@addr-host.

   o  Otherwise, if the address structure's [IMAP] addr-mailbox is non-
      NIL, the sort value for the address is its addr-mailbox.

   o  If none of the above conditions are met, the sort value for the
      address is the empty string.






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4.  The DISPLAYFROM and DISPLAYTO Sort Keys

   This document introduces two new [SORT] sort-keys, DISPLAYFROM and
   DISPLAYTO.

   A message's sort value under the DISPLAYFROM ordering MUST be derived
   as follows from the [IMAP] env-from value of the [IMAP] envelope
   structure resulting from a FETCH ENVELOPE on the message:

   o  If the env-from value is NIL, the message's sort value is the
      empty string.

   o  Otherwise, the message's sort value is the DISPLAY sort value of
      the first [IMAP] address in the envelope structure's env-from.

   A message's sort value under the DISPLAYTO ordering MUST be derived
   as follows from the [IMAP] env-to value of the [IMAP] envelope
   structure resulting from a FETCH ENVELOPE on the message:

   o  If the env-to value is NIL, the message's sort value is the empty
      string.

   o  Otherwise, the message's sort value is the DISPLAY sort value of
      the first [IMAP] address in the envelope structure's env-to.


5.  Formal Syntax

   The following syntax specification uses the Augmented Backus-Naur
   Form (ABNF) notation as specified in [RFC4234].  [IMAP] defines the
   non-terminal "capability" and [SORT] defines "sort-key".

capability    =/ "SORT=DISPLAY"

sort-key      =/ "DISPLAYFROM" | "DISPLAYTO"


6.  Security Considerations

   This document defines an additional IMAP4 capability.  As such, it
   does not change the underlying security considerations of [IMAP].
   The author believes that no new security issues are introduced with
   this additional IMAP4 capability.


7.  Internationalization Considerations

   DISPLAYFROM and DISPLAYTO are string-based sort criteria.  As stated



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   in [SORT], the collations mandated by I18NLEVEL=1 or I18NLEVEL=2 from
   [RFC5255] MUST be followed when sorting such strings.

   The DISPLAYFROM and DISPLAYTO orderings sort on the full decoded
   [IMAP] addr-name, when present.  They do not attempt to parse this
   string in a locale- or language-dependent manner in order to
   determine and sort on some semantically meaningful substring such as
   the surname.


8.  IANA Considerations

   [IMAP] capabilities are registered by publishing a standards track or
   IESG-approved experimental RFC.  This document constitutes
   registration of the SORT=DISPLAY capability in the [IMAP]
   capabilities registry.


9.  Normative References

   [IMAP]     Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
              4rev1", RFC 3501, March 2003.

   [RFC2047]  Moore, K., "MIME (Multipurpose Internet Mail Extensions)
              Part Three: Message Header Extensions for Non-ASCII Text",
              RFC 2047, November 1996.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 4234, October 2005.

   [RFC5255]  Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet
              Message Access Protocol Internationalization", RFC 5255,
              June 2008.

   [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 5322,
              October 2008.

   [SORT]     Crispin, M. and K. Murchison, "Internet Message Access
              Protocol - SORT and THREAD Extensions", RFC 5256,
              June 2008.








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Author's Address

   Dan Karp
   Zimbra
   701 First St.
   Sunnyvale, CA  94089
   USA

   Email: dkarp@zimbra.com
   URI:   http://www.zimbra.com









































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