Settle in, this may take some time.
A friend has a home office. They have ADSL and a Netgear 639 (i think) router.
They are currently set up with their static IP forwarding port 25 to their exchange server on the internal network 10.0.1.10
That server is handling mail for domain x.com and is running as x.local's DC, DNS and exchange server.
the MX record passes mail to the public ip of their router which obviously forwards it to the exchange server and does its job.
Now they have a second company. With a second domain y.com which they want an exchange server for.
How can we do this with only 1 IP (the ISP has allocated 4 static public IPs but I dont know how to use them).