Postfix will use different IP addresses to send mail on a server with virtual IPs: Eth0 = 184.108.40.206 (rdns=mx.example.com) eth0:0 = 220.127.116.11 (rdns=mx.example.com) eth0:1 = 18.104.22.168 (rdns=mx.example.com) eth0:2 = 22.214.171.124 (rdns=mx.example.com) The problem is that if it sends mail from one of the virtual ip the reverse dns will never match and much of the mail gets labeled as SPAM even thought the SPF record clearly states that receiving mail from that IP for that domain is OK. The possible fix to the problem was to smtp_bind_address in /etc/postfix/main.cf to 126.96.36.199, but if you do so all the other processes that will internally contact the server at 127.0.0.1 will fail and your mail will back up in the queue(postqueue -p). So I've already tried changing the master.cf config to: 188.8.131.52:10025 inet n - - - - smtpd But it did not work apparently with an ISPCONFIG setup there are more things to consider (AMAVIS, etc,etc,etc). Just grepping for 127.0.0.1 in postfix returns many other things to change: /etc/postfix# grep -R '127.0.0.1' * main.cf:#inet_interfaces = 184.108.40.206,127.0.0.1 main.cf:content_filter = amavis:[127.0.0.1]:10024 main.cf~:content_filter = amavis:[127.0.0.1]:10024 main.cf~2:content_filter = amavis:[127.0.0.1]:10024 main.cf~3:content_filter = amavis:[127.0.0.1]:10024 master.cf:127.0.0.1:10025 inet n - - - - smtpd master.cf~:127.0.0.1:10025 inet n - - - - smtpd mysql-virtual_client.cf:hosts = 127.0.0.1 mysql-virtual_client.cf~:hosts = 127.0.0.1 mysql-virtual_domains.cf:hosts = 127.0.0.1 mysql-virtual_domains.cf~:hosts = 127.0.0.1 mysql-virtual_email2email.cf:hosts = 127.0.0.1 mysql-virtual_email2email.cf~:hosts = 127.0.0.1 mysql-virtual_forwardings.cf:hosts = 127.0.0.1 mysql-virtual_forwardings.cf~:hosts = 127.0.0.1 mysql-virtual_mailboxes.cf:hosts = 127.0.0.1 mysql-virtual_mailboxes.cf~:hosts = 127.0.0.1 mysql-virtual_recipient.cf:hosts = 127.0.0.1 mysql-virtual_recipient.cf~:hosts = 127.0.0.1 mysql-virtual_relaydomains.cf:hosts = 127.0.0.1 mysql-virtual_relaydomains.cf~:hosts = 127.0.0.1 mysql-virtual_relayrecipientmaps.cf:hosts = 127.0.0.1 mysql-virtual_relayrecipientmaps.cf~:hosts = 127.0.0.1 mysql-virtual_sender.cf:hosts = 127.0.0.1 mysql-virtual_sender.cf~:hosts = 127.0.0.1 mysql-virtual_transports.cf:hosts = 127.0.0.1 mysql-virtual_transports.cf~:hosts = 127.0.0.1 So my question is, am I going about this all wrong??? Is there an easier way to force postfix to use the main ip for outgoing and still service 127.0.0.1? HELP!!!!