master.cf

submission inet n       -       -       -       -       smtpd
  -o syslog_name=postfix/submission
  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_sasl_authenticated_header=yes
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
  -o milter_macro_daemon_name=ORIGINATING
dovecot-spamass   unix  -       n       n       -       -       pipe
  flags=DRhu user=vmail:vmail argv=/usr/bin/spamc -u ${user}@${nexthop} -e /usr/lib/dovecot/deliver -f ${sender} -d ${user}@${nexthop} -a ${recipient}