Sieve Email Filtering: Sieves and Display Directives in XML
RFC 5784
Internet Engineering Task Force (IETF) N. Freed
Request for Comments: 5784 S. Vedam
Category: Standards Track Sun Microsystems
ISSN: 2070-1721 March 2010
Sieve Email Filtering: Sieves and Display Directives in XML
Abstract
This document describes a way to represent Sieve email filtering
language scripts in XML. Representing Sieves in XML is intended not
as an alternate storage format for Sieve but rather as a means to
facilitate manipulation of scripts using XML tools.
The XML representation also defines additional elements that have no
counterparts in the regular Sieve language. These elements are
intended for use by graphical user interfaces and provide facilities
for labeling or grouping sections of a script so they can be
displayed more conveniently. These elements are represented as
specially structured comments in regular Sieve format.
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/rfc5784.
Freed & Vedam Standards Track [Page 1]
RFC 5784 An XML Representation for Sieve March 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
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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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 4
3. Grammatical Structure of Sieve . . . . . . . . . . . . . . . . 4
4. XML Representation of Sieve . . . . . . . . . . . . . . . . . 6
4.1. XML Display Directives . . . . . . . . . . . . . . . . . . 9
4.2. Structured Comments . . . . . . . . . . . . . . . . . . . 10
4.3. Validation . . . . . . . . . . . . . . . . . . . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . . 12
7.2. Informative References . . . . . . . . . . . . . . . . . . 13
Appendix A. Extended Example . . . . . . . . . . . . . . . . . . 14
Appendix B. XML Schema for Sieves in XML . . . . . . . . . . . . 21
Appendix C. Relax NG Schema for Sieves in XML . . . . . . . . . . 24
Appendix D. Stylesheet for Conversion from XML . . . . . . . . . 26
Appendix E. Acknowledgements . . . . . . . . . . . . . . . . . . 32
Freed & Vedam Standards Track [Page 2]
RFC 5784 An XML Representation for Sieve March 2010
1. Introduction
Sieve [RFC5228] is a language for filtering email messages at or
around the time of final delivery. It is designed to be
implementable on either a mail client or mail server. It is meant to
be extensible, simple, and independent of access protocol, mail
architecture, and operating system, and it is intended to be
manipulated by a variety of different user interfaces.
Some user interface environments have extensive existing facilities
for manipulating material represented in XML [XML]. While adding
support for alternate data syntaxes may be possible in most if not
all of these environments, it may not be particularly convenient to
do so. The obvious way to deal with this issue is to map Sieves into
XML, possibly on a separate back-end system, manipulate the XML, and
convert it back to normal Sieve format.
The fact that conversion into and out of XML may be done as a
separate operation on a different system argues strongly for defining
a common XML representation for Sieve. This way, different front-end
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