SIEVE Email Filtering: Spamtest and VirusTest Extensions
RFC 3685

Document Type RFC - Proposed Standard (February 2004; No errata)
Obsoleted by RFC 5235
Last updated 2015-10-14
Stream ISE
Formats plain text pdf html bibtex
Stream ISE state (None)
Consensus Boilerplate Unknown
Document shepherd No shepherd assigned
IESG IESG state RFC 3685 (Proposed Standard)
Telechat date
Responsible AD Ned Freed
Send notices to (None)
Network Working Group                                           C. Daboo
Request for Comments: 3685                  Cyrusoft International, Inc.
Category: Standards Track                                  February 2004

        SIEVE Email Filtering: Spamtest and VirusTest Extensions

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

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

Abstract

   The SIEVE mail filtering language "spamtest" and "virustest"
   extensions permit users to use simple, portable commands for spam and
   virus tests on email messages.  Each extension provides a new test
   using matches against numeric 'scores'.  It is the responsibility of
   the underlying SIEVE implementation to do the actual checks that
   result in values returned by the tests.

Table of Contents

   1.  Introduction and Overview  . . . . . . . . . . . . . . . . . .  2
   2.  SIEVE Extensions . . . . . . . . . . . . . . . . . . . . . . .  3
       2.1.  General Considerations . . . . . . . . . . . . . . . . .  3
       2.2.  Test spamtest. . . . . . . . . . . . . . . . . . . . . .  3
       2.3.  Test virustest . . . . . . . . . . . . . . . . . . . . .  4
   3.  Security Considerations  . . . . . . . . . . . . . . . . . . .  5
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  6
       4.1.  spamtest registration. . . . . . . . . . . . . . . . . .  6
       4.2.  virustest registration . . . . . . . . . . . . . . . . .  6
   5.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  7
       5.1.  Normative References . . . . . . . . . . . . . . . . . .  7
       5.2.  Informative References . . . . . . . . . . . . . . . . .  7
   6.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  7
   7.  Intellectual Property Rights Statement . . . . . . . . . . . .  7
   8.  Author's Address . . . . . . . . . . . . . . . . . . . . . . .  8
   9.  Full Copyright Statement . . . . . . . . . . . . . . . . . . .  9

Daboo                       Standards Track                     [Page 1]
RFC 3685        SIEVE Spamtest and VirusTest Extensions    February 2004

1.  Introduction and Overview

   SIEVE scripts are frequently being used to do spam and virus
   filtering based on either implicit script tests (e.g., tests for
   'black-listed' senders directly encoded in the SIEVE script), or via
   testing messages modified by some external spam or virus checker that
   handled the message prior to SIEVE.  The use of third-party spam and
   virus checker tools poses a problem since each tool has its own way
   of indicating the result of its checks.  These usually take the form
   of a header added to the message, the content of which indicates the
   status using some syntax defined by the particular tool.  Each user
   has to then create their own SIEVE scripts to match the contents of
   these headers to do filtering.  This requires the script to stay in
   synchronization with the third party tool as it gets updated or
   perhaps replaced with another.  Thus scripts become tied to specific
   environments, and lose portability.

   The purpose of this document is to introduce two SIEVE tests that can
   be used to implement 'generic' tests for spam and viruses in messages
   processed via SIEVE scripts.  These tests return a string containing
   a range of numeric values that indicate the severity of spam or
   viruses in a message, or a string that indicates the message has not
   passed through any spam or virus checking tools.  The spam and virus
   checks themselves are handled by the underlying SIEVE implementation
   in whatever manner is appropriate, and the implementation maps the
   results of these checks into the numeric ranges defined by the new
   tests.  Thus a SIEVE implementation can have a spam test that
   implicitly checks for third-party spam tool headers and determines
   how those map into the spamtest numeric range.

   In order to do numeric comparisons against the returned strings,
   server implementations MUST also support the SIEVE relational
   [RELATIONAL] extension, in addition to the extensions described here.
   All examples below assume the relational extension is present.

   Conventions for notations are as in [SIEVE] section 1.1, including
   use of [KEYWORDS].

   The term 'spam' is used in this document to refer to unsolicited or
   unwanted email messages.  This document does not attempt to define
Show full document text