Mailbox Integration

Use of the imip-agent software should not affect the solutions chosen to store mail received by your mail system. However, the software does support direct connections to mail storage solutions employing the LMTP protocol. See the LMTP guide for more information.

It can, however, be useful to see how delivery to various kinds of mailboxes and mail storage is done, in case you have not already decided on a particular solution. Tested solutions are as follows:



Cyrus is a mail storage system that exposes mailboxes using the IMAP protocol

The Cyrus documentation provides a guide on integrating Cyrus with MTAs.

Dovecot is a mail server that supports IMAP and POP3. It can be configured to serve mail stored in traditional mailbox formats

The Dovecot documentation provides guides for integrating Dovecot with Exim and with Postfix.

Traditional Unix mailboxes for local system users

If routing is defined for local users and if local SMTP is employed, no other mail storage solution is required.

With the traditional Unix mailbox approach, no further configuration should be necessary because Exim and Postfix support delivery to such mailboxes amongst their normal configuration rules. The rest of this document describes the integration of these mail transport agents with other mail storage solutions using LMTP.


Example configuration files for Exim are distributed in conf/exim/lmtp:




Delivers messages to Cyrus via LMTP


Delivers messages to Dovecot via LMTP

On Debian systems, these files would be copied into the /etc/exim4/conf.d/transport directory.

The mailbox integration for local system users is also found in the conf/exim/lmtp directory:




Routes messages for local system users to Cyrus


Routes messages for local system users to Dovecot

Meanwhile, both the conf/exim/ldap and conf/exim/simple directories provide the following files. The appropriate file for the chosen configuration should be used:




Routes messages for local virtual users to Cyrus


Routes messages for local virtual users to Dovecot

On Debian systems, these files would be copied into the /etc/exim4/conf.d/router directory. Depending on whether system user identities are to be employed for mail or whether genuine virtual identities (not connected to the system) are to be employed, one type (local_system or local_lmtp) of these files should be selected.


Example configuration files for Postfix are distributed in conf/postfix/lmtp:




Configures LMTP delivery for local recipients (for installation into /etc/postfix)

Enables LMTP delivery for local recipients


Defines LMTP delivery methods for local recipients

These files provide example definitions for the and transport files that typically reside under /etc/postfix. Their contents can be merged with those files as appropriate.


Note that remarks about permissions management in the LMTP guide, concerning communication with mail storage systems such as Cyrus, also apply when getting MTAs such as Postfix to communicate with those systems. Consequently, it may be necessary to add the dedicated MTA system user to a specially-created lmtp group. For example:

adduser postfix lmtp

See the system users guide for more information on the lmtp group.