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Versions: 00

Network Working Group                                           C. Daboo
Internet-Draft                              Cyrusoft International, Inc.
Expires: August 4, 2004                                 February 4, 2004


                 SIEVE Email Filtering: MIME Extension
                       draft-daboo-sieve-mime-00

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on August 4, 2004.

Copyright Notice

   Copyright (C) The Internet Society (2004). All Rights Reserved.

Abstract

   This document describes the SIEVE Email Filtering "mime" extension
   which adds a new test for testing the values of MIME headers in a
   message.

Open Issues (will be removed prior to publication as an RFC)

   a.  How to deal with MIME encoding/splitting of parameters, i18n etc

Change History (to be removed prior to publication as an RFC)

   Changes:
   a.  Initial draft.




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Table of Contents

   1.  Introduction and Overview  . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
   3.  SIEVE MIME Extension . . . . . . . . . . . . . . . . . . . . .  3
   3.1 General Considerations . . . . . . . . . . . . . . . . . . . .  3
   3.2 Test "mime"  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . .  5
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  5
   5.1 mime registration  . . . . . . . . . . . . . . . . . . . . . .  5
       References . . . . . . . . . . . . . . . . . . . . . . . . . .  6
       Author's Address . . . . . . . . . . . . . . . . . . . . . . .  6
       Intellectual Property and Copyright Statements . . . . . . . .  7






































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1. Introduction and Overview

   The SIEVE Email Filtering [RFC3028] specification currently does not
   provide a way to test the values of MIME [RFC2045] part headers
   within a message. Currently, all that can be done is a standard
   "header" test against the top-level message headers (and thus the
   top-level MIME part of the message). However, it is handy to be able
   to check for values in any MIME part headers, or check for the
   presence of specific MIME types etc. This extension introduces a new
   "mime" test that allows the values of every MIME part header to be
   tested.

2. Conventions Used in This Document

   Conventions for notations are as in [RFC3028] section 1.1, including
   use of [RFC2119].

3. SIEVE MIME Extension

3.1 General Considerations

   SIEVE implementations that implement the "mime" test have an
   identifier of "mime" for use with the capability mechanism. If the
   "mime" test is used in a SIEVE script, the corresponding capability
   item MUST appear in the script's "require" statement. Like the
   "header" test in [RFC3028], folding of long header lines (as
   described in [RFC2822]) is removed prior to interpretation of the
   data.

3.2 Test "mime"

           Syntax:   mime [COMPARATOR] [MATCH-TYPE]
                     <header-names: string-list>
                     [<parameter-names: string-list>]
                     <key-list: string-list>

   The "mime" test evaluates to true if any MIME header name, or any
   parameter within a MIME header name, matches any key. The type of
   match is specified by the optional match argument, which defaults to
   ":is" if not provided, as specified in section 2.6 of [RFC3028].

   If no parameter-names argument is present, then the entire content of
   the headers specified in the header-names argument is evaluated. So
   if a message contained the MIME header:

       Content-Type: image/jpeg; filename="example.jpg"

   these tests on that MIME header evaluate as follows:



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       mime :contains ["Content-Type"] ["image"]    => true
       mime :contains ["Content-Type"] ["jpg"]      => true
       mime :contains ["Content-Type"] ["filename"] => true
       mime :contains ["Content-Type"] ["gif"]      => false

   If the parameter-names argument is present, then only the content of
   matching MIME parameters in the specified headers are evaluated. So
   if a message contained the MIME header:

       Content-Type: image/jpeg; filename="example.jpg"

   these tests on that MIME header evaluate as follows:

       mime :contains ["Content-Type"] ["filename"] ["image"]    => false
       mime :contains ["Content-Type"] ["filename"] ["jpg"]      => true
       mime :contains ["Content-Type"] ["filename"] ["filename"] => false
       mime :contains ["Content-Type"] ["filename"] ["gif"]      => false
       mime :contains ["Content-Type"] ["name"] ["jpg"]          => false

   If the parameter-names argument is present, but contains a single
   empty string, then the content of specified MIME header, excluding
   any parameters, will be evaluated. So if a message contained the MIME
   header:

       Content-Type: image/jpeg; filename="example.jpg"

   these tests on that MIME header evaluate as follows:

       mime :contains ["Content-Type"] [""] ["image"]    => true
       mime :contains ["Content-Type"] [""] ["jpg"]      => false
       mime :contains ["Content-Type"] [""] ["filename"] => false
       mime :contains ["Content-Type"] [""] ["gif"]      => false

   Like the "header" test in [RFC3028], this test returns true if any
   combination of the header-names, parameters-names and key-list
   arguments match.

   Like the "header" test in [RFC3028], if a MIME header listed in the
   header-names argument exists, it contains the null key (""). However,
   if the named header is not present, it does not contain the null key.
   So if a message contained the MIME header:

       Content-Caffeine: C8H10N4O2

   these tests on that header evaluate as follows:

       mime :is ["Content-Caffeine"] [""]       => false
       mime :contains ["Content-Caffeine"] [""] => true



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   A similar behaviour applies to MIME parameters specified by the
   parameter-names argument:

       Content-Caffeine: C8H10N4O2; param1=example

   these tests on that parameter evaluate as follows:

      mime :is ["Content-Caffeine"] ["param1"] [""]       => false
      mime :contains ["Content-Caffeine"] ["param1"] [""] => true


4. Security Considerations

   The "mime" extension does not raise any security considerations that
   are not present in the base [RFC3028] protocol, and these issues are
   discussed in [RFC3028].

5. IANA Considerations

   The following template specifies the IANA registration of the Sieve
   extension specified in this document:

5.1 mime registration

       To: iana@iana.org
       Subject: Registration of new Sieve extension

       Capability name: mime
       Capability keyword: mime
       Capability arguments:
                     mime [COMPARATOR] [MATCH-TYPE]
                     <header-names: string-list>
                     [<parameter-names: string-list>]
                     <key-list: string-list>
       Standards Track/IESG-approved experimental RFC number: this RFC
       Person and email address to contact for further information:

         Cyrus Daboo
         Cyrusoft International, Inc.
         5001 Baum Blvd., Suite 780,
         Pittsburgh, PA 15213
         U.S.A.

         <mailto:daboo@cyrusoft.com>

   This information should be added to the list of sieve extensions
   given on http://www.iana.org/assignments/sieve-extensions.




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References

   [RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part One: Format of Internet Message
              Bodies", RFC 2045, November 1996.

   [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.

   [RFC3028]  Showalter, T., "Sieve: A Mail Filtering Language", RFC
              3028, January 2001.


Author's Address

   Cyrus Daboo
   Cyrusoft International, Inc.
   5001 Baum Blvd.
   Suite 780
   Pittsburgh, PA  15213
   US

   EMail: daboo@cyrusoft.com

























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   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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Acknowledgment

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