Message Organization Working Group D. Karp Internet-Draft Zimbra Updates: 5256 (if approved) February 24, 2010 Intended status: Standards Track Expires: August 28, 2010 Display-based Address Sorting for the IMAP4 SORT Extension draft-ietf-morg-sortdisplay-03 Abstract This document describes an IMAP protocol extension enabling server- side message sorting on the commonly-displayed portion of the From and To header fields. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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. This Internet-Draft will expire on August 28, 2010. Copyright Notice Copyright (c) 2010 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 Karp Expires August 28, 2010 [Page 1] Internet-Draft IMAP4 Display-based Address Sorting February 2010 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 BSD License. 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 Criteria . . . . . . . . . . 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 Karp Expires August 28, 2010 [Page 2] Internet-Draft IMAP4 Display-based Address Sorting February 2010 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] FROM and TO orderings sort messages lexically on the [IMAP] addr-mailbox of the first address in the message's From and To headers, respectively. This document provides two alternate orderings, DISPLAYFROM and DISPLAYTO, which sort messages 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 both 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 criteria 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, apply the procedure from [RFC5255] section 4.6. (That is, decode any [RFC2047] encoded-words and convert the resulting character string into a charset valid for the currently-active [RFC4790] collation, with a default of UTF-8.) If the resulting octet 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. Karp Expires August 28, 2010 [Page 3] Internet-Draft IMAP4 Display-based Address Sorting February 2010 4. The DISPLAYFROM and DISPLAYTO Sort Criteria This document introduces two new [SORT] sort criteria, DISPLAYFROM and DISPLAYTO. A message's sort value under these orderings MUST be derived as follows: A "derived-addr" value is created from the [IMAP] envelope structure resulting from a FETCH ENVELOPE on the message. For DISPLAYFROM, the derived-addr value is the [IMAP] env-from value. For DISPLAYTO, the derived-addr value is the [IMAP] env-to value. o If the derived-addr 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 derived-addr value. 5. Formal Syntax The following syntax specification uses the Augmented Backus-Naur Form (ABNF) notation as specified in [RFC5234]. [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 in [SORT], the active [RFC4790] collation as per [RFC5255] MUST be used 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. Karp Expires August 28, 2010 [Page 4] Internet-Draft IMAP4 Display-based Address Sorting February 2010 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. [RFC4790] Newman, C., Duerst, M., and A. Gulbrandsen, "Internet Application Protocol Collation Registry", RFC 4790, March 2007. [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. [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. Karp Expires August 28, 2010 [Page 5] Internet-Draft IMAP4 Display-based Address Sorting February 2010 Author's Address Dan Karp Zimbra 3401 Hillview Avenue Palo Alto, CA 94304 USA Email: dkarp@zimbra.com URI: http://www.zimbra.com Karp Expires August 28, 2010 [Page 6]