IMAP FILTER Sieve plugin for Pigeonhole

Relevant specifications
=======================

	doc/rfc/draft-bosch-imap-filter-sieve-00.txt

Introduction
============

Normally, Sieve filters can either be applied at initial mail delivery or
triggered by certain events in the Internet Message Access Protocol (IMAPSIEVE;
RFC 6785). The user can configure which Sieve scripts to run at these instances,
but it is not possible to trigger the execution of Sieve scripts manually.
However, this could be very useful; e.g, to test new Sieve rules and to
re-filter messages that were erroneously handled by an earlier version of the
Sieve scripts involved.

Pigeonhole provides the imap_filter_sieve plugin, which provides a vendor-
defined IMAP extension called "FILTER=SIEVE". This adds a new "FILTER" command
that allows applying a mail filter (a Sieve script) on a set of messages that
match the specified searching criteria.

This plugin is experimental and the specification is likely to change.

Configuration
=============

The IMAP FILTER Sieve plugin is activated by adding it to the mail_plugins
setting for  the imap protocol:

protocol imap {
	mail_plugins = $mail_plugins imap_filter_sieve
}

Currently, no other settings specific to this plugin are defined. It uses the
normal configuration settings used by the LDA Sieve plugin at delivery.

The sieve_before and sieve_after scripts are currently ignored by this plugin.

Example
-------

protocol imap {
  # Space separated list of plugins to load (default is global mail_plugins).
  mail_plugins = $mail_plugins imap_filter_sieve
}

plugin {
  sieve_global = /usr/lib/dovecot/sieve-global.d
}