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.
Configuration and Use¶
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.
