[exim] relay based on sender address and sender host

Hello,

I just installed exim on a server to act as a gateway and it works fine.
Now here comes the special demand: from inside the network an Exchange server sends mails to the gateway where the sender address looks like localpart@???. Exim itself sends these messages back because it is configured to relay these message to the Exchange server when they were coming from the outside. Now, how can I configure exim to check the sender IP/name (Exchange server) and the localpart of an email address to relay these messages to a specific mail server (IP/name) outside the network?

I thought about combing sender_address_relay and hostlist relay_hosts in a router, but is it the right approach?


Any help would appreciated

Gerd