This has happend twice today and I can figure out why.
For some reason our edge transport server stops delivering incoming mail. There is no error listed or reason why it would stop. The only noticable thing is in the QUEUE, it has our hubtransport/domain listed instead of the nice little check mark icon, it has that confused looking icon that says i'm stuck so i am holding onto all of your messages.
While the messages are getting stuck in the queue we are able to send out going messages through the system. TEST-EDGESYNC also works perfectly and there the two servers seem to be able to talk to each other with no problem. I am able to ping, start-edgesync get-transportserver ect.... and everything works.
There is nothing in the event log and there is no error messages generated. To get the mail flowing again Ihave to stop and restar the Microsoft Exchange Transport service on my edge server.
I have since completely restarted my Edge server and the issue came back again...
It's an easy fix to restart the Transport service, but i dont want to do that 20 times day.