Sophos Firewall <> Server 2012 DC, DNS <> Server 2012
Issue: On the internal Server 2012 I have some apps running that require to send out some mails over SMTP. At first I was not able to establish a connection at all, thinking the Win Firewall was at fault.
However, I completely disabled the Windows Firewall (just for testing purposes) allowed SMTP Packets (TLS, SSL, Plain) (587, 465, 25) on the Sophos Firewall and tried it with a ton of different SMTP-Servers. However, I can see that DNS-Resolution is working but the connection times out. On the Sophos Firewall Live Log I do not see any dropped packets anymore and at this point I am not sure what else could be the problem. If I put the Server in the DMZ everything is working fine.