Reference: http://wiki2.dovecot.org/AuthDatabase/LDAP

aptitude install dovecot-imapd dovecot-pop3d dovecot-ldap

/etc/dovecot/conf.d/10-auth.conf:

...
!include auth-ldap.conf.ext
..

/etc/dovecot/conf.d/10-mail.conf:

...
mail_uid = 200
mail_gid = 200
...
first_valid_uid = 200
...

/etc/dovecot/dovecot-ldap.conf.ext:

hosts = localhost

auth_bind = yes

base = ou=qmail, o=mrzesty

user_attrs = =home=/var/qmail/maildirs/%{ldap:mailMessageStore}

user_filter = (&(objectClass=qmailUser)(uid=%u))

pass_attrs = =home=/var/qmail/maildirs/%{ldap:mailMessageStore}

pass_filter = (&(objectClass=qmailUser)(uid=%u))

Activate fail2ban to block brute force attacks.

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