I swapped over from SonicWall to a Cisco ASA. Everything seemed to work except now some of my Exchange email gets stuck in the external queues. I get errors 421 4.4.2 Connection Dropped and 451 4.4.2 Timeout errors.
But it is not all email. I can send a message to gmail and it works like lightening. Someone else sends to gmail and it sits. Then any message I send to gmail after that sits in behind for 30 to 180 minutes. But I can send to other domains no problem. It is not limited to gmail, this happens to several domains but there is no pattern.
There is one user who this happens to routinely but it is not restricted to him.
I have rebooted exchange, cleared the queues, changed my transport settings from straight out and through a smarthost, run exchange analyzer and done my updates. Same thing.