However, I have an external spam filter that I use that authenticates my log in by authenticating through POP3. Previously I was using a PFsense router that I simply port forwarded any requests for port 110 from the IP of the spam filter to the Exchange server which worked great. This doesn't seem to work with Sophos though. If I make a DNAT rule to forward 110 to the exchange server and a Firewall rule to allow it, I still see the request being blocked in the log.
I figure this is because of the built in POP3 proxy, even if it's turned off. However, when I turn it on and configure it, in the logs I see the spam filter talking to the UTM but the UTM is not passing the request on to the Exchange server.
This is how I have it configured:
Global: Allowed networks is set to the IP of the spam filter
Advanced:
Skip transparent: A separate listing for both IP of the Exchange server and the IP of the spam filter
Is what I'm trying to do possible?
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