I have been searching around on how to do this.... Ive tried it a couple of times but it has not worked yet.. right now ive got a windows machine running doing this:

incoming port of : 1110 gets sent to mail.attbi.com:110 and
incoming port of : 2555 gets sent to mail.attbi.com:25

Using my computer as a gateway... (proper terms I hope.) Id like to set up my linux box to do that....

Then... if I get it working, is there a way to limit this access by IP? so only certain people I know about can use that mapping?

I am running Redhat 8.0 and ive been playing with iptables to try and do this... but I don't think I am understanding becuase I couldn't get it to work at all...

So if anyone could better explain how I would go about doing this, that would be awesome. Thanks.
-Brian.