Linux/Mailserver/Small Office Smarthost

This configuration is based on Ubuntu 12.04 LTS

• preparing the system

mkdir /srv/mail/virtual
groupadd -g 5000 vmail
useradd -s /usr/sbin/nologin -u 5000 -g 5000 vmail
id vmail

dovecot

• /etc/dovecot/conf.d/10-auth.conf

auth_mechanisms = plain            # optional: login

#!include auth-master.conf.ext     # disable
!include auth-passwdfile.conf.ext

• /etc/dovecot/conf.d/10-logging.conf

log_path = /var/log/dovecot

auth_debug = yes    # for debugging only
mail_debug = yes    #
verbose_ssl = yes   #

• /etc/dovecot/conf.d/10-mail.conf

mail_location = maildir:/srv/mail/virtual/%d/%n

• /etc/dovecot/conf.d/10-master.conf

service auth {
...
  unix_listener /var/spool/postfix/private/auth {
    mode = 0660
    # Assuming the default Postfix user and group
    user = postfix
    group = postfix        
  }
  ...
}

touch /var/log/dovecot
chown vmail:vmail /var/log/dovecot
chmod 660