SieveNetwork Working Group K. MurchisonInternet-DraftRequest for Comments: 5233 Carnegie Mellon University Obsoletes: 3598(if approved) June 15, 2006 Expires: December 17, 2006January 2008 Category: Standards Track Sieve EmailFiltering --Filtering: Subaddress Extensiondraft-ietf-sieve-rfc3598bis-05Status ofthisThis MemoBy 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 ofThis document specifies an Internet standards track protocol for the InternetEngineering Task Force (IETF), its areas,community, andits working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents validrequests discussion and suggestions fora maximumimprovements. Please refer to the current edition ofsix monthsthe "Internet Official Protocol Standards" (STD 1) for the standardization state andmay 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 liststatus ofcurrent Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The listthis protocol. Distribution ofInternet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on December 17, 2006. Copyright Notice Copyright (C) The Internet Society (2006).this memo is unlimited. Abstract On email systems that allow for 'subaddressing' or 'detailed addressing' (e.g., "ken+sieve@example.org"), it is sometimes desirable to make comparisons against these sub-parts of addresses. This document defines an extension to the Sievemail filtering languageEmail Filtering Language that allows users to compare against the user and detail sub-parts of an address. Table of Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 3....................................................2 2. ConventionsusedUsed inthis document . . . . . . . . . . . . . . 4This Document ...............................2 3. Capability Identifier. . . . . . . . . . . . . . . . . . . . 5...........................................2 4. Subaddress Comparisons. . . . . . . . . . . . . . . . . . . . 6..........................................2 5. IANA Considerations. . . . . . . . . . . . . . . . . . . . . 8.............................................5 6. Security Considerations. . . . . . . . . . . . . . . . . . . 9.........................................5 7. Normative References. . . . . . . . . . . . . . . . . . . . . 9............................................5 Appendix A. Acknowledgments. . . . . . . . . . . . . . . . . . . 10........................................6 Appendix B. Changes sinceRFC3598 . . . . . . . . . . . . . . . . 11 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . . . 13RFC 3598 .................................6 1. Introduction Subaddressing is the practice of augmenting the local-part of an [RFC2822] address with some 'detail' information in order to give some extra meaning to that address. One common way of encoding 'detail' information into the local-part is to add a 'separator character sequence', such as "+", to form a boundary between the 'user' (original local-part) and 'detail' sub-parts of the address, much like the "@" character forms the boundary between the local-part and domain. Typical uses of subaddressing might be: o A message addressed to "ken+sieve@example.org" is delivered into a mailbox called "sieve" belonging to the user "ken". o A message addressed to "5551212#123@example.com" is delivered to the voice mailbox number "123" at phone number "5551212". This document describes an extension to the Sieve language defined by[I-D.ietf-sieve-3028bis][RFC5228] for comparing against the 'user' and 'detail' sub-parts of an address. 2. ConventionsusedUsed inthis documentThis 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]. 3. Capability Identifier The capability string associated with the extension defined in this document is "subaddress". 4. Subaddress Comparisons Test commands that act exclusively on addresses may take the optional tagged arguments ":user" and ":detail" to specify what sub-part of the local-part of the address will be acted upon. NOTE: In most cases, the envelope "to" address is the preferred address to examine for subaddress information when the desire is to sort messages based on how they were addressed so as to get to a specific recipient. The envelope address is, after all, the reason a given message is being processed by a given sieve script for a given user. This is particularly true when mailing lists, aliases, and 'virtual domains' are involved since the envelope may be the only source of detail information for the specific recipient. NOTE: Because the encoding of detailed addresses are site and/or implementation specific, using the subaddress extension on foreign addresses (such as the envelope "from" address or originator header fields) may lead to inconsistent or incorrect results. The ":user" argument specifies the user sub-part of the local-part of an address. If the address is not encoded to contain a detail sub- part, then ":user" specifies the entireleft-sideleft side of the address (equivalent to ":localpart"). The ":detail" argument specifies the detail sub-part of the local- part of an address. If the address is not encoded to contain a detail sub-part, then thetest evaluatesaddress fails tofalse.match any of the specified keys. If a zero-length string is encoded as the detail sub-part, then ":detail" resolves to the empty value (""). NOTE: If the encoding method used for detailed addresses utilizes a separator character sequence, and the separator character sequence occurs more than once in the local-part, then the logic used to split the address isimplementation defined,implementation-defined and is usually dependent on the format used by the encompassing mail system. Implementations MUST make sure that the encoding method used for detailed addresses matches that which is used and/or allowed by the encompassing mail system, otherwise unexpected results might occur. Note that the mechanisms used to define and/or query the encoding method used by the mail system are outside the scope of this document. The ":user" and ":detail" address parts are subject to the same rules and restrictions as the standard address parts defined in[I-D.ietf- sieve-3028bis][RFC5228], Section 2.7.4. For convenience, the "ADDRESS-PART" syntax element defined in[I-D.ietf-sieve-3028bis][RFC5228], Section2.7.42.7.4, is augmented here as follows: ADDRESS-PART =/ ":user" / ":detail" A diagram showing the ADDRESS-PARTs ofaan email address where the detail information follows a separator character sequence of "+" is shown below: :user "+" :detail "@" :domain \-----------------/ :local-part A diagram showing the ADDRESS-PARTs of a email address where the detail information precedes a separator character sequence of "--" is shown below: :detail "--" :user "@" :domain \------------------/ :local-part Example (where the detail information follows "+"): require["subaddress",["envelope", "subaddress", "fileinto"]; # In this example the same user account receives mail for both # "ken@example.com" and "postmaster@example.com" # File all messages to postmaster into a single mailbox, # ignoring the :detail part. if envelope :user "to" "postmaster" { fileinto "inbox.postmaster"; stop; } # File mailing list messages (subscribed as "ken+mta-filters"). if envelope :detail "to" "mta-filters" { fileinto "inbox.ietf-mta-filters"; } # Redirect all mail sent to "ken+foo". if envelope :detail "to" "foo" { redirect "ken@example.net"; } 5. IANA ConsiderationsThis document requests thatThe following template specifies the IANAupdate the entry forregistration of the"subaddress"subaddress Sieve extensionto point atspecified in thisdocumentdocument. This registration replaces that from RFC 3598: To: iana@iana.org Subject: Registration of new Sieve extension Capability name: subaddress Description: Adds the ':user' andto update':detail' address parts for use with thecontactaddress and envelope tests RFC number: RFC 5233 Contact address: The Sieve discussion list <ietf-mta-filters@imc.org> This informationwithhas been added to theauthor's address.list of Sieve extensions given on http://www.iana.org/assignments/sieve-extensions. 6. Security Considerations Security considerations are discussed in[I-D.ietf-sieve-3028bis].[RFC5228]. It is believed that this extension does not introduce any additional security concerns. 7. Normative References[I-D.ietf-sieve-3028bis] Showalter, T. and P. Guenther, "Sieve: An Email Filtering Language", draft-ietf-sieve-3028bis-06 (work in progress), March 2006.[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2822] Resnick, P., "Internet Message Format", RFC 2822, April 2001. [RFC5228] Guenther, P., Ed., and T. Showalter, Ed., "Sieve: An Email Filtering Language", RFC 5228, January 2008. Appendix A. Acknowledgments Thanks to Tim Showalter, Alexey Melnikov, Michael Salmon, Randall Gellens, Philip Guenther, Jutta Degener, Michael Haardt, Ned Freed, Mark Mallett, and Barry Leiba for their help with this document. Appendix B. Changes sinceRFC3598RFC 3598 o Discussion of how the user and detail information is encoded now uses generic language. o Added note detailing that this extension is most useful when used on the envelope "to" address. o Added note detailing that this extension isn't very useful on foreign addresses (envelope "from" or originator header fields). o Fixed envelope test example to only use "to" address. o Replaced ":user" example with one that doesn't produce unexpected behavior. o Refer to the zero-length string ("") as "empty" instead of "null" (perdraft-ietf-sieve-3028bis)RFC 5228). o Use only RFC 2606 domains in examples. o Miscellaneous editorial changes. Author's Address Kenneth Murchison Carnegie Mellon University 5000 Forbes Avenue Cyert Hall 285 Pittsburgh, PA 15213USUSA Phone: +1 412 268 2638Email:EMail: murch@andrew.cmu.edu Full Copyright Statement Copyright (C) The IETF Trust (2008). 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