I have a red hat 7 box running iptables doing port fw for a web server inside my lan (also a linux box). I want to use sendmail to process forms on the web server and can't seem to get port 25 open from the inside.

I guess the question is:

How do I get a web server to use sendmail from inside a NAT box?

Order of devices:
dsl router=public ip address
nat box=translates ip and port fw
webserver=private ip address