My messages are sitting in the queue with status ready but are never delivered. My machine is 10.20.30.40 running DNS with primary DNS as 10.20.30.40 and secondary DNS as 10.20.30.1. 10.20.30.1 is router running NAT. public address is NAT to 10.20.30.40 for mail.mydomain.com. I really do not want to lose my mail server today again. Does anyone know why this may be?

I set the DNS settings in Exchange to use the adapter setting for IPv4. Problem solved. I guess it was not so bad.