Because of an ADSL line upgrade we were forced to change our router.
I plugged in the new router, set up the ISP username and password, gave it the right internal IP address (A.B.C.2) and hey presto, we were on the internet again, and VoIP was working.
However, our Exchange mailserver, on the SBS server at A.B.C.253, while able to send mail out, was not collecting any external mail.
We got 5 static IP addresses from our ISP, viz:
" * the network address is: X.Y.Z.192
* your router/hub address is: X.Y.Z.198
* your subnet mask address is: 255.255.255.248 if you have 5 Static IP addresses or 255.255.255.240 if you have 13 Static IP addresses
Your computers can use addresses from X.Y.Z.193 to X.Y.Z.197 "
In DNS our mailserver is set to X.Y.Z.193, but the router is X.Y.Z.198
I think we simply need to set up a route in the router that will convert external IP = X.Y.Z.193 to internal IP = A.B.C.253