As part of a move to a new building we are going to stop using our own firewall and have the university provide us that service. We have tested de-activating our current firewall rules and NAT and having the university activate them on their side. Every time we've tested, exchange does not work externally, but I can send and receive emails inside our network. The only firewall rules that I had on our firewall was for http, https and smtp. We do use webmail as well - but that should be covered under the https/smtp ports.
The university looked at their firewall and didn't see any traffic coming in our out. I found an error in the event viewer that said exchange unable to find underlying transport and listed the tcp/udp port of 47001. There has never been a firewall rule for that.
Any ideas what rules would be needed/what the issue might be? As part of this change I also have to change the default gateway from our firewall to the university's gateway. I do that on the network properties... is this in Exchange some place?