[expert] Port Forwarding I guess

[Orlando Lewis]

I have NT Server Exchange 5.5 that I want to run behind a RedHat 6.1 box.
The Redhat box is connected to the internet and does IP masquerading for the
local intranet. Could someone recommend a solution that will allow me to use
this mail server behind a linux box.  I want all mail
handled by the NT box and all Ftp services handled by the Linux box.

Thanks in advance.....