port forwarding

[Bill Holt]

First, thanks for the advice on postfix config, I forget the name, you know who you are. Here's the set up, I'm running postfix/spamassassin as a mail gateway for the exchange boxes (by the way this thing rocks!), one problem which I totally forgot about was exchange OWA. I now need to do port-forwarding on the linux box to support owa. Do I have to build this into the kernel? Does anyone have experience with this?
Thanks