I would need some suggestions on setting up an internal exim email relay server. Here below is the scenario:
I have 2 MS Exchange servers for 2 customers respectively: abc and xyz. They are on 2 different internal networks and they can not talk directly. I want to setup a email relay server with exim to relay email from email@example.com to firstname.lastname@example.org, vice versa. In another way to discribe this: I want to put a static DNS record for xyz.com on abc’s exchange server, so that it will send email to relay server if destination email is on xyz.com domain and relay server forward email to xyz’s exchange server; Similiar setup on xyz’s exchange server. If destination email is on any other domains, send normally to internet.
So it is like a conditional email relay. Any suggestions?