outbound emails are not sent via nginx smtp proxy

[cybermass]

All emails ending at the destination note the sender as the actual backend
and not nginx proxy. How can I force smtp outbound through nginx? I tried
smtp_bind_address = proxy.ip.addr in main.cf for postfix. And tried adding
an SNAT rule in iptables to route through the proxy with no luck. Any
advice?

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,249355,249355#msg-249355