[CentOS] iptables port forwarding

i'm having a problem viewing logs on forwarded ports from the firewall
to another server, i forwarded mail(port 25) from the firewall to an
internal server. The problem is when i try to view the logs it just
shows the firewall ip as the sender and not the original sender.


-- 
Regards,
Mark Quitoriano, CCNA
http://www.atamanetworks.com