We have two Exchange servers, one 2003 one 2010. We have a block of 10 IP's. The configuration is similar to below.
Internal IP 192.168.1.254
External IP 188.8.131.52
Internal IP 192.168.1.253
External IP 184.108.40.206
I forwarded 80, 443, and 3389 from 220.127.116.11 to 192.168.1.253 just like the 2003 box is forwareded. The problem is when I set up NAT. I configured 1 to 1 NAT just like the 2003 box, but the external IP is not showing correctly. I then make a Dynamic NAT exception, just like the 2003 box, but then mail wont go out from the 2010 box.