Pigeonhole Sieve Interpreter

The Pigeonhole project provides Sieve support as a plugin for Dovecot’s Local Delivery Agent (LDA) and also for its LMTP service. The plugin implements a Sieve interpreter, which filters incoming messages using a script specified in the Sieve language (RFC 5228). The Sieve script is provided by the user and, using that Sieve script, the user can customize how incoming messages are handled. Messages can be delivered to specific folders, forwarded, rejected, discarded, etc.

Supported Features

Sieve language has various extensions. You can find more information about the extensions from the Sieve Mail Filtering Language Charter or the Sieve.info wiki page.

Note

Sieve doesn’t support running external programs.

The Pigeonhole Sieve interpreter recognizes the following Sieve extensions:

Extension

Support Status

Default Enabled

Purpose

body

supported

yes

Allows evaluating the body of a message

copy

supported

yes

Allows storing and forwarding messages without canceling the implicit keep

date

supported (v0.1.12+)

yes

Adds the ability to test date and time values in various ways

duplicate

supported (v0.4.3+)

yes

Allows detecting duplicate message deliveries

editheader

supported (v0.3.0+)

no

Adds the ability to add and remove message header fields

encoded-character

supported

yes

Allows encoding special characters numerically

enotify

supported (v0.1.3+)

yes

Provides the ability to send notifications by various means (currently only mailto)

envelope

supported

yes

Allows evaluating envelope parts, i.e. sender and recipient

environment

supported (v0.4.0+)

yes

Allows testing against various labeled values from the execution environment

fileinto

supported

yes

Allows storing messages in folders other than INBOX

foreverypart

supported (v0.4.14+)

yes

Allows iterating through the message’s MIME parts

ihave

supported (v0.2.4+)

yes

Adds the ability to test for support of Sieve extensions and dynamically invoke their use

imap4flags

supported

yes

Allows adding IMAP flags to stored messages

imapsieve

supported (v0.4.14+)

no (plugin)

Provides access to special environment items when executing at IMAP events

include

supported (v0.4.0+)

yes

Allows including other Sieve scripts

index

supported (v0.4.7+)

yes

Allows matching specific header field instances by index

mailbox

supported (v0.1.10+)

yes

Provides a mailbox existence check and allows creating mailboxes upon fileinto

mboxmetadata

supported (v0.4.7+)

no

Provides access to mailbox METADATA entries

mime

supported (v0.4.14+)

yes

Allows testing parts of structured MIME header fields

extracttext

supported (v0.4.14+)

yes

Allows extracting text from individual message MIME parts

regex

supported

yes

Provides regular expression match support

reject

supported

yes

Allows rejecting messages with a rejection bounce message

relational

supported

yes

Provides relational match support

servermetadata

supported (v0.4.7+)

no

Provides access to server METADATA entries

spamtest

supported (v0.1.16+)

no

Implements a uniform way to test against headers added by spam filters

subaddress

supported

yes

Allows testing against delimited elements of the local part of addresses

vacation

supported

yes

Provides auto-responder functionality, e.g. for when the user is on vacation

vacation-seconds

supported (0.2.3+)

no

Extends vacation extension with the ability to send vacation responses with intervals of seconds rather than days

variables

supported

yes

Adds variables support to the language

virustest

supported (v0.1.16+)

no

Implements a uniform way to test against headers added by virus scanners

imapflags(obsolete draft)

deprecated

no

Old version of imap4flags (for backwards compatibility with CMU Sieve)

notify

deprecated

no

Old version of enotify (for backwards compatibility with CMU Sieve)

The following Dovecot-specific Sieve extensions are available for the Pigeonhole Sieve interpreter:

Extension

Support Status

Default Enabled

Purpose

vnd.dovecot.debug

supported (v0.3.0+)

no

Allows logging debug messages

vnd.dovecot.environment

supported (v0.4.14+)

no

Extends the standard “environment” extension with extra items and a variables namespace for direct access

vnd.dovecot.execute

Extprograms Plugin (v0.3+)

no

Implements executing a pre-defined set of external programs with the option to process string data through the external program

vnd.dovecot.extdata

Extdata Plugin

no

Allows a Sieve script to lookup information from a datasource external to the script

vnd.dovecot.filter

plugin (v0.3+)

no

Implements filtering messages through a pre-defined set of external programs

vnd.dovecot.pipe

Pipe Plugin (v0.2), Pigeonhole Sieve Extprograms Plugin (v0.3+)

no

Implements piping messages to a pre-defined set of external programs

vnd.dovecot.report

supported (v0.4.14+)

no

Implements sending Messaging Abuse Reporting Format (MARF) reports (RFC 5965

Note

Not all extensions are enabled by default, as shown in the table above. Deprecated extensions, extensions that add the ability to change messages, extensions that require explicit configuration and extensions that are still under development are not enabled without explicit configuration. This means that the sieve_extensions or sieve_global_extensions settings need to be adjusted accordingly. Also, for plugins it is not enough to add the plugin name to the sieve_plugins setting; the extensions introduced by the plugin also need to be enabled explicitly.

ManageSieve server

To give users the ability to upload their own Sieve scripts to your server, i.e. without the need for shell or FTP access, you can use the ManageSieve protocol. This is also provided by the Pigeonhole project. It is available as a separate Dovecot service. Its configuration and use is explained on the Pigeonhole ManageSieve page.