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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 3501 (ref. 'IMAP') (Obsoleted by RFC 9051) Summary: 2 errors (**), 0 flaws (~~), 1 warning (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Message Organization Working Group D. Karp 3 Internet-Draft Zimbra 4 Updates: 5256 (if approved) February 24, 2010 5 Intended status: Standards Track 6 Expires: August 28, 2010 8 Display-based Address Sorting for the IMAP4 SORT Extension 9 draft-ietf-morg-sortdisplay-03 11 Abstract 13 This document describes an IMAP protocol extension enabling server- 14 side message sorting on the commonly-displayed portion of the From 15 and To header fields. 17 Status of this Memo 19 This Internet-Draft is submitted to IETF in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF), its areas, and its working groups. Note that 24 other groups may also distribute working documents as Internet- 25 Drafts. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 The list of current Internet-Drafts can be accessed at 33 http://www.ietf.org/ietf/1id-abstracts.txt. 35 The list of Internet-Draft Shadow Directories can be accessed at 36 http://www.ietf.org/shadow.html. 38 This Internet-Draft will expire on August 28, 2010. 40 Copyright Notice 42 Copyright (c) 2010 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (http://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the BSD License. 55 Table of Contents 57 1. Conventions Used in This Document . . . . . . . . . . . . . . . 3 58 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 3. DISPLAY Sort Value for an Address . . . . . . . . . . . . . . . 3 60 4. The DISPLAYFROM and DISPLAYTO Sort Criteria . . . . . . . . . . 4 61 5. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 4 62 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 63 7. Internationalization Considerations . . . . . . . . . . . . . . 4 64 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 65 9. Normative References . . . . . . . . . . . . . . . . . . . . . 5 66 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5 68 1. Conventions Used in This Document 70 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 71 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 72 document are to be interpreted as described in [RFC2119]. 74 2. Introduction 76 The [SORT] extension to the [IMAP] protocol provides a means for 77 server-based sorting of messages. It defines a set of sort criteria 78 and the mechanism for determining the sort value of a message for 79 each such ordering. 81 The [SORT] FROM and TO orderings sort messages lexically on the 82 [IMAP] addr-mailbox of the first address in the message's From and To 83 headers, respectively. This document provides two alternate 84 orderings, DISPLAYFROM and DISPLAYTO, which sort messages based on 85 the first From or To address's [IMAP] addr-name (generally the same 86 as its [RFC5322] display-name), when present. 88 A server that supports the full [SORT] extension as well as both the 89 DISPLAYFROM and DISPLAYTO sort criteria indicates this by returning 90 "SORT=DISPLAY" in its CAPABILITY response. 92 3. DISPLAY Sort Value for an Address 94 For the purposes of the sort criteria defined in this document, the 95 sort value for an [IMAP] address structure is defined as follows: 97 o If the address structure's [IMAP] addr-name is non-NIL, apply the 98 procedure from [RFC5255] section 4.6. (That is, decode any 99 [RFC2047] encoded-words and convert the resulting character string 100 into a charset valid for the currently-active [RFC4790] collation, 101 with a default of UTF-8.) If the resulting octet string is not 102 the empty string, use it as the sort value for the address. 104 o Otherwise, if the address structure's [IMAP] addr-mailbox and 105 [IMAP] addr-host are both non-NIL, the sort value for the address 106 is addr-mailbox@addr-host. 108 o Otherwise, if the address structure's [IMAP] addr-mailbox is non- 109 NIL, the sort value for the address is its addr-mailbox. 111 o If none of the above conditions are met, the sort value for the 112 address is the empty string. 114 4. The DISPLAYFROM and DISPLAYTO Sort Criteria 116 This document introduces two new [SORT] sort criteria, DISPLAYFROM 117 and DISPLAYTO. A message's sort value under these orderings MUST be 118 derived as follows: 120 A "derived-addr" value is created from the [IMAP] envelope structure 121 resulting from a FETCH ENVELOPE on the message. For DISPLAYFROM, the 122 derived-addr value is the [IMAP] env-from value. For DISPLAYTO, the 123 derived-addr value is the [IMAP] env-to value. 125 o If the derived-addr value is NIL, the message's sort value is the 126 empty string. 128 o Otherwise, the message's sort value is the DISPLAY sort value of 129 the first [IMAP] address in the derived-addr value. 131 5. Formal Syntax 133 The following syntax specification uses the Augmented Backus-Naur 134 Form (ABNF) notation as specified in [RFC5234]. [IMAP] defines the 135 non-terminal "capability" and [SORT] defines "sort-key". 137 capability =/ "SORT=DISPLAY" 139 sort-key =/ "DISPLAYFROM" / "DISPLAYTO" 141 6. Security Considerations 143 This document defines an additional IMAP4 capability. As such, it 144 does not change the underlying security considerations of [IMAP]. 145 The author believes that no new security issues are introduced with 146 this additional IMAP4 capability. 148 7. Internationalization Considerations 150 DISPLAYFROM and DISPLAYTO are string-based sort criteria. As stated 151 in [SORT], the active [RFC4790] collation as per [RFC5255] MUST be 152 used when sorting such strings. 154 The DISPLAYFROM and DISPLAYTO orderings sort on the full decoded 155 [IMAP] addr-name, when present. They do not attempt to parse this 156 string in a locale- or language-dependent manner in order to 157 determine and sort on some semantically meaningful substring such as 158 the surname. 160 8. IANA Considerations 162 [IMAP] capabilities are registered by publishing a standards track or 163 IESG-approved experimental RFC. This document constitutes 164 registration of the SORT=DISPLAY capability in the [IMAP] 165 capabilities registry. 167 9. Normative References 169 [IMAP] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 170 4rev1", RFC 3501, March 2003. 172 [RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions) 173 Part Three: Message Header Extensions for Non-ASCII Text", 174 RFC 2047, November 1996. 176 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 177 Requirement Levels", BCP 14, RFC 2119, March 1997. 179 [RFC4790] Newman, C., Duerst, M., and A. Gulbrandsen, "Internet 180 Application Protocol Collation Registry", RFC 4790, 181 March 2007. 183 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 184 Specifications: ABNF", STD 68, RFC 5234, January 2008. 186 [RFC5255] Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet 187 Message Access Protocol Internationalization", RFC 5255, 188 June 2008. 190 [RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322, 191 October 2008. 193 [SORT] Crispin, M. and K. Murchison, "Internet Message Access 194 Protocol - SORT and THREAD Extensions", RFC 5256, 195 June 2008. 197 Author's Address 199 Dan Karp 200 Zimbra 201 3401 Hillview Avenue 202 Palo Alto, CA 94304 203 USA 205 Email: dkarp@zimbra.com 206 URI: http://www.zimbra.com