Sieve Extension for Converting Messages before Delivery
RFC 6558

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Internet Engineering Task Force (IETF)                       A. Melnikov
Request for Comments: 6558                                 Isode Limited
Category: Standards Track                                       B. Leiba
ISSN: 2070-1721                                                    K. Li
                                                     Huawei Technologies
                                                              March 2012

        Sieve Extension for Converting Messages before Delivery

Abstract

   This document describes how the "CONVERT" IMAP extension can be used
   within the Sieve mail filtering language to transform messages before
   final delivery.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6558.

Copyright Notice

   Copyright (c) 2012 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
   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 Simplified BSD License.

Melnikov, et al.             Standards Track                    [Page 1]
RFC 6558                      Sieve CONVERT                   March 2012

Table of Contents

   1. Introduction ....................................................2
      1.1. Conventions Used in This Document ..........................2
   2. "convert" Action ................................................2
      2.1. Interaction with Other Tests and Actions ...................3
      2.2. "convert" as a Test ........................................4
   3. Examples ........................................................5
      3.1. Example 1 ..................................................5
      3.2. Example 2 ..................................................5
      3.3. Example 3 ..................................................5
      3.4. Example 4 ..................................................6
   4. Security Considerations .........................................7
   5. IANA Considerations .............................................7
   6. Acknowledgements ................................................7
   7. Normative References ............................................7

1.  Introduction

   The IMAP "CONVERT" extension [RFC5259] adds an IMAP command for
   performing client-controlled conversions on whole messages or their
   body parts.  This document defines a similar extension to the Sieve
   mail filtering language [RFC5228], which reuses the conversion
   parameters and framework established by IMAP CONVERT.

1.1.  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 RFC 2119 [RFC2119].

   Conventions for notations are as in Sieve [RFC5228], Section 1.1.

2.  "convert" Action

   Usage: convert  <quoted-from-media-type: string>
                   <quoted-to-media-type: string>
                   <transcoding-params: string-list>

   The "convert" action specifies that all body parts with a media type
   [RFC2046] (sometimes called "MIME type") equal to <quoted-from-media-
   type> be converted to the media type in <quoted-to-media-type> using
   conversion parameters specified in <transcoding-params>.  Each
   conversion parameter value has the following syntax: "<transcoding-
   param-name>=<transcoding-param-value>", where <transcoding-param-
   name> and <transcoding-param-value> are defined in CONVERT [RFC5259].
   Messages that don't have any body parts with the <quoted-from-media-
   type> media type are not affected by the conversion.

Melnikov, et al.             Standards Track                    [Page 2]
RFC 6558                      Sieve CONVERT                   March 2012

   The "convert" action can be used with Sieve MIME Part Tests
   [RFC5703], in the case that some, but not all of the body parts need
   to be converted, or where different body parts might require
   different conversions.  When the "convert" action appears in a