Last week I got call from one of my colleagues complaining about the amount of spam she's receiving, so I installed SA and implemented some restricted options in postfix smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination, reject_invalid_hostname, reject_non_fqdn_hostname, reject_non_fqdn_sender, reject_rbl_client list.dsbl.org, reject_rbl_client cbl.abuseat.org, reject_rbl_client, dnsbl.sorbs.net, reject_rbl_client spam.dnsbl.sorbs.net, reject_rbl_client korea.services.net, reject_rbl_client zen.spamhaus.org, reject_rbl_client pbl.spamhaus.org, reject_rbl_client sbl.spamhaus.org, permit but later she called complaining that she cannot send emails using our SMTP server so for me it was what the hell is going one? later I found that Postfix is picky about the order of your options so if you do reject_non_fqdn_hostn