I have 2 Exchange 2007 client access/hub transport/edge servers. Both were operating fine. Lets call them exg01 and exg02. Well, today, I disabled the send connector for exg01 and later noticed that we were getting delivery delay reports. In looking at the queues, I see that there are several hundred outbound messages that exg01 was attempting to relay to exg02 and failing with 451 5.7.3 Cannot achieve Exchange Server authentication. I ahve already checked my default recieve connectors for each server to ensure that TLS and Exchange servers options were enabled like I had seen suggested in other forums.
Any idea whats going on here and how to resolve?