I am in the middle of migrating from Exchange 2003 to Exchange 2010 SP1.
I have moved one mailbox over to the new server EXCHANGE2010 . For some reason if an internal email is sent from someone on EXCHANGE2003 (the old server), it is not delivered to the new mailbox on EXCHANGE2010.
Where should I look to debug this problem? What logs should I consult?
Update: I found the messages in Queues on the old server, listed as messages with an unreachable destination.