Pigeonhole IMAPSieve Plugins
============================

As defined in the base specification (RFC 5228
[http://tools.ietf.org/html/rfc5228]), the Sieve language is used only during
delivery. However, in principle, it can be used at any point in the processing
of an email message.RFC 6785 [http://tools.ietf.org/html/rfc6785] defines the
use of Sieve filtering in IMAP, operating when messages are created or their
attributes are changed. This feature extends both Sieve and IMAP. Therefore,
Pigeonhole provides both an IMAP plugin and a Sieve plugin.

The 'sieve_imapsieve' plugin implements the 'imapsieve' extension for the Sieve
filtering language, adding functionality for using Sieve scripts from within
IMAP. The 'imap_sieve' plugin for IMAP adds the 'IMAPSIEVE' capability to the
'imap' service. The basic 'IMAPSIEVE' capability allows attaching a Sieve
script to a mailbox for any mailbox by setting a special IMAP METADATA entry.
This way, users can configure Sieve scripts that are run for IMAP events in
their mailboxes.

Beyond the standard, the Pigeonhole implementation also adds the ability for
administrators to configure Sieve scripts outside the user's control, that are
run either before or after a user's script if there is one.

This plugin is available for <Pigeonhole.txt> v0.4.14 and higher (available for
Dovecot v2.2.24). The plugins are included in the Pigeonhole package and are
therefore implicitly compiled and installed with Pigeonhole itself.

Configuration
-------------

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

---%<-------------------------------------------------------------------------
protocol imap {
  mail_plugins = $mail_plugins imap_sieve
}
---%<-------------------------------------------------------------------------

This will only enable support for administrator scripts. User scripts are only
supported when additionally a Sieve URL is configured using the imapsieve_url
plugin setting. This URL points to the <ManageSieve>
[Pigeonhole.ManageSieve.txt] server that users need to use to upload their
Sieve scripts. This URL will be shown to the client in the IMAP CAPABILITY
response as 'IMAPSIEVE=<URL>'.

The Sieve plugin is activated by adding it to the sieve_plugins setting:

---%<-------------------------------------------------------------------------
sieve_plugins = sieve_imapsieve
---%<-------------------------------------------------------------------------

This plugin registers the 'imapsieve' extension with the Sieve interpreter.
This extension is enabled implicitly, which means that it does not need to be
added to the 'sieve_extensions' setting.

Note that the 'imapsieve' extension can only be used in a Sieve script that is
invoked from IMAP. When it is used in the active delivery script, it will cause
runtime errors. To make a Sieve script suitable for both delivery and IMAP, the
availability of the extension can be tested using the 'ihave' test (RFC 5463
[http://tools.ietf.org/html/rfc5463]) as usual.

The following settings are recognized the "imap_sieve" plugin:

imapsieve_url = :
  If configured, this setting enables support for user Sieve scripts in IMAP.
  So, leave this unconfigured if you don't want users to have the ability to
  associate Sieve scripts with mailboxes. This has no effect on the
  administrator-controlled Sieve scripts explained below. The value is an URL
  pointing to the <ManageSieve> [Pigeonhole.ManageSieve.txt] server that users
  must use to upload their Sieve scripts; e.g.,'sieve://sieve.example.com'.

imapsieve_mailboxXXX_name = :
  This setting configures the name of a mailbox for which administrator scripts
  are configured. The `XXX' in this setting is a sequence number, which allows
  configuring multiple associations between Sieve scripts and mailboxes. The
  settings defined hereafter with matching sequence numbers apply to the
  mailbox named by this setting. The sequence of configured mailboxes ends at
  the first missing 'imapsieve_mailboxXXX_name' setting. This setting supports
  wildcards with a syntax compatible with the IMAP LIST command, meaning that
  this setting can apply to multiple or even all ("*") mailboxes.

imapsieve_mailboxXXX_before = :

imapsieve_mailboxXXX_after = :
  When an IMAP event of interest occurs, these sieve scripts are executed
  before and after any user script respectively. These settings each specify
  the location of a single sieve script. The semantics of these settings are
  very similar to the 'sieve_before' and 'sieve_after' settings: the specified
  scripts form a sequence together with the user script in which the next
  script is only executed when an (implicit) keep action is executed.

imapsieve_mailboxXXX_causes = :
  Only execute the administrator Sieve scripts for the mailbox configured with
  'imapsieve_mailboxXXX_name' when one of the listed 'IMAPSIEVE' causes
  [https://tools.ietf.org/html/rfc6785#section-4.3] apply (currently either
  'APPEND', 'COPY', or 'FLAG'. This has no effect on the user script, which is
  always executed no matter the cause.

imapsieve_mailboxXXX_from = :
  Only execute the administrator Sieve scripts for the mailbox configured with
  'imapsieve_mailboxXXX_name' when the message originates from the indicated
  mailbox. This setting supports wildcards with a syntax compatible with the
  IMAP LIST command

See <Replacing antispam plugin with IMAPSieve> [HowTo.AntispamWithSieve.txt] as
example on how to use this.

(This file was created from the wiki on 2019-06-19 12:42)
