Sieve Email Filtering: Detecting Duplicate Deliveries
draft-ietf-appsawg-sieve-duplicate-01
APPSAWG S. Bosch
Internet-Draft November 4, 2013
Intended status: Standards Track
Expires: May 8, 2014
Sieve Email Filtering: Detecting Duplicate Deliveries
draft-ietf-appsawg-sieve-duplicate-01
Abstract
This document defines a new test command "duplicate" for the "Sieve"
email filtering language. This test adds the ability to detect
duplicate message deliveries. The main application for this new test
is handling duplicate deliveries commonly caused by mailing list
subscriptions or redirected mail addresses. The detection is
normally performed by matching the message ID to an internal list of
message IDs from previously delivered messages. For more complex
applications, the "duplicate" test can also use the content of a
specific header or other parts of the message.
Status of this Memo
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This Internet-Draft will expire on May 8, 2014.
Copyright Notice
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document authors. All rights reserved.
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Internet-Draft Sieve: Detecting Duplicate Deliveries November 2013
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Test "duplicate" . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Interaction with Other Sieve Extensions . . . . . . . . . 7
4. Sieve Capability Strings . . . . . . . . . . . . . . . . . . . 7
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . . . 7
5.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . . . 8
5.3. Example 3 . . . . . . . . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
This is an extension to the Sieve filtering language defined by RFC
5228 [SIEVE]. It adds a test to determine whether a certain message
was seen before by the delivery agent in an earlier execution of the
Sieve script. This can be used to detect and handle duplicate
message deliveries.
Duplicate deliveries are a common side-effect of being subscribed to
a mailing list. For example, if a member of the list decides to
reply to both the user and the mailing list itself, the user will get
one copy of the message directly and another through mailing list.
Also, if someone cross-posts over several mailing lists to which the
user is subscribed, the user will receive a copy from each of those
lists. In another scenario, the user has several redirected mail
addresses all pointing to his main mail account. If one of the
user's contacts sends the message to more than one of those
addresses, the user will likely receive more than a single copy.
Using the "duplicate" extension, users have the means to detect and
handle such duplicates, e.g. by discarding them, marking them as
"seen", or putting them in a special folder.
Duplicate messages are normally detected using the Message-ID header
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