• LDA
• Postfix

Dovecot LDA with Postfix

System users

If you wish you use deliver for all system users on a single domain mail host you can do it by editing mailbox_command parameter in

/etc/postfix/main.cf (postconf(5)):

mailbox_command = /usr/local/libexec/dovecot/deliver
#  or
mailbox_command = /usr/libexec/dovecot/deliver
#  or
mailbox_command = /usr/lib/dovecot/deliver
#  or wherever it was installed in your system.

Then run postfix reload and that is it.

Some detailed config files and examples at http://heinous.org/wiki/Virtual_Domains%2C_Postfix%2C_Dovecot_LDA%2C_and_LDAP

Virtual users

Dovecot LDA is very easy to use on large scale installations with Postfix virtual domains support, just add a dovecot service in /etc/postfix/master.cf (master(5)):

dovecot   unix  -       n       n       -       -       pipe
  flags=DRhu user=vmail:vmail argv=/usr/local/libexec/dovecot/deliver -f ${sender} -d ${recipient}

An example using address extensions (ie user+extension@domain.com (don't forget to define the proper recipient_delimiter in Postfix's main.cf)) to deliver to the folder 'extension' in your maildir (If you wish to preserve the case of ${extension}, remove the 'hu' flags, and be sure to utilize Modifiers in your dovecot.conf for mail locations and other configuration parameters that are expecting lower case):

dovecot unix    -       n       n       -       -      pipe
  flags=DRhu user=vmail:vmail argv=/usr/local/libexec/dovecot/deliver -f ${sender} -d ${user}@${nexthop} -n -m ${extension}

# or with v1.1.2+ if you have a INBOX/ namespace prefix:
dovecot unix    -       n       n       -       -      pipe
  flags=DRhu user=vmail:vmail argv=/usr/local/libexec/dovecot/deliver -f ${sender} -d ${user}@${nexthop} -n -m INBOX/${extension}

This example ignores address extensions (ie user+extension@domain.com delivers just like user@domain.com):

dovecot   unix  -       n       n       -       -       pipe
  flags=DRhu user=vmail:vmail argv=/usr/lib/dovecot/deliver -f ${sender} -d ${user}@${nexthop}

Replace vmail above with your virtual mail user account.

Then set virtual_transport to dovecot in /etc/postfix/main.cf:

dovecot_destination_recipient_limit = 1
virtual_mailbox_domains = your.domain.here
virtual_transport = dovecot 

And remember to run

postfix reload

Virtual users with multiple uids/gids

If you need multiple uids/gids you'll need to set deliver setuid root. See the LDA main page how to do this securely.

Postfix mail_debug caveat

This is a problem with Dovecot versions older than v1.0.1:

Be sure that the mail_debug setting is commented out in dovecot.conf, because otherwise the postfix sendmail replacement will be started in the debugger using debugger_command and delayed for five seconds. It is not enough to set mail_debug to no, because postfix's sendmail command checks for the existence of the MAIL_DEBUG environment variable, which is created by the dovecot lda as soon as a mail_debug setting is present.

Postfix with a NFS mail store

If you are experiencing problems with deliver processes hanging when delivering to a NFS mail store, it's likely that the deliver process is hanging while waiting for free locks. The occurrence of this can be greatly reduced, if not eradicated, by forcing Postfix to only deliver to the same recipient one at a time.

dovecot_destination_concurrency_limit = 1