You can put something like this into /etc/postfix/main.cf: Code: smtpd_recipient_restrictions = reject_invalid_hostname, reject_unknown_recipient_domain, reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, reject_rbl_client relays.ordb.org, reject_rbl_client opm.blitzed.org, reject_rbl_client list.dsbl.org, reject_rbl_client sbl.spamhaus.org, reject_rbl_client blackholes.easynet.nl, reject_rbl_client cbl.abuseat.org, permit and restart Postfix.