Dovecot IMAP configuration

We are using PAM for the passdb and LDAP for the userdb. We will also configure the LDA (Local delivery agent) because we will use dovecot for delivery as it is able to use sieve scripts. The configuration file /etc/dovecot/dovecot.conf could look similar to the following

protocols = imap imaps
disable_plaintext_auth = yes
syslog_facility = mail

passdb pam {
}

userdb ldap {
  args = /etc/dovecot/dovecot-ldap.conf
}

We have to tell postfix that it should use dovecot for delivery be editing /etc/postfix/main.cf

virtual_transport = dovecot
dovecot_destination_recipient_limit = 1

In the /etc/postfix/master.cf we have to create a service which is called dovecot

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

Now dovecot is responsible for delivering.

LDAP interface configuration

With /etc/dovecot/dovecot-ldap.conf we configure where to find the data in the LDAP directory for the userdb

hosts = localhost
base = ou=people, dc=example, dc=com
ldap_version = 3
scope = subtree
user_attrs = homeDirectory=home,mailbox=mail
user_filter = (|(uid=%u)(maildrop=%u))
user_global_uid = 110
user_global_gid = 110

Logrotate for LDA

If you use the log file like mentioned above you really should configure logrotate to do the rotation. Else this file can get really big. Do this by adding the file /etc/logrotate.d/dovecot-deliver

/var/vmail/dovecot-deliver.log {
  weekly
  rotate 14
  compress
}

Using `sieve` scripting for delivering

I've decided to use 2 kinds of sieve scripts. A global one for every user who doesn't write his own and a per user script. Therefore we edit /etc/dovecot/dovecot.conf to contain

protocol lda {
  postmaster_address = postmaster@example.com
  log_path = /var/vmail/dovecot-deliver.log
  auth_socket_path = /var/run/dovecot/auth-master
  mail_plugins = cmusieve                          # that's for the sieve scripting
}

socket listen {
  master {
    path = /var/run/dovecot/auth-master
    mode = 0600
    user = vmail
  } 
}

plugin {
   sieve_global_path = /var/vmail/globalsieverc
   sieve=/var/vmail/sieve/%n.%d.sieve
}

Now we can create the global script

touch /var/vmail/globalsieverc
chown vmail: /var/vmail/globalsieverc

and edit /var/vmail/globalsieverc to contain something like

require ["fileinto"];
# Move spam to spam folder
if anyof ( header :contains "X-Spam-Flag" "YES",
           header :contains "Subject" "***SPAM***" ) {
  fileinto "spam";
  stop;
}

If you want to use you own per user script you might create a file like /var/vmail/sieve/michael.derhammer.net.sieve. This should be readable by dovecot and overwrites the global one.

LDAP interface configuration

Logrotate for LDA

Using sieve scripting for delivering

Using `sieve` scripting for delivering