dovecot - Dec 2014 - dovecot-auth only configuration

I am configuring a dovecot-auth only installation. Postfix will use dovecot for
sasl auth.

Here is the configuration I?ve settled upon.  I welcome suggestions for
improving this setup.

Thanks.

# doveconf -n
# 2.2.15: /usr/local/etc/dovecot/dovecot.conf
# OS: FreeBSD 9.3-RELEASE-p5 amd64  
auth_mechanisms = plain login
mail_max_userip_connections = 80
mail_privileged_group = mail
passdb {
  args = scheme=SHA512-CRYPT /var/db/dovecot.users
  driver = passwd-file
}
protocols = none
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
  }
  user = root
}
userdb {
  args = /var/db/dovecot.users
  driver = passwd-file
}
verbose_proctitle = yes

? 
Dan Langille
http://langille.org/