ACL_check_mail:
  deny message = envelope sender $sender_address blacklisted.
       senders = ${if exists{CONFDIR/local_sender_blacklist}\
                             {CONFDIR/local_sender_blacklist}\
                             {}}

  deny message = sender IP address $sender_host_address is blacklisted here.
       hosts = ${if exists{CONFDIR/local_host_blacklist}\
                             {CONFDIR/local_host_blacklist}\
                             {}}

  deny !verify = sender/callout=5s,defer_ok

  accept