Preserving Client IP address for SMTP traffic

Thanks for the tip Aaron. Netcat and wireshark helped identify the real problem.

 

 

My test servers was actually connected to an old Cisco load balancer. Even though we change the default route on the server, the Cisco sent the responses back to the firewall instead of the F5.

 

 

I also created a forwarding IP virtual server so we could access the real server.