TMG 2010 SP2 - After applying SP2 to TMG 2010 server Exchange EDGE server SMTP communication with the HUB server will fail with “Unrecognized command” error

ISSUE:

Users are unable to Receive External Emails and if you look at Queue monitor on Edge server you would see following error

Exchange EDGE server SMTP communication with the HUB server will fail with “Unrecognized command” error.

Environment :

TMG 2010 , Exchange 2010 SP1 , Edge 

CAUSE :

After applying SP2 to TMG 2010 server, the ‘SMTP Filter’ for the SMTP publishing rule will be reset to the default state. Exchange EDGE server SMTP communication with the HUB server will fail with “Unrecognized command” error.

Workaround :

- Login to TMG server and Uncheck the ‘SMTP Filter’ for the SMTP publishing rule.

- Retry the Queue on the EDGE server.

Root Cause :

After applying SP2 to TMG 2010 server, the ‘SMTP Filter’ for the SMTP publishing rule will be reset to the default state.

Exchange EDGE server SMTP communication with the HUB server will fail with “Unrecognized command” error.