Hi guys, we encountered the message queue build up on the hub transport server after update from forefront sp1 to sp2 and together we installed the hotfix roll up 2 as well, the last error message from exchange is Message deferred by the categorizer agent, checked in the forefront programlog.txt not much info just stating that it is not able to get the update from internet which is correct as we did not allow internet on the server, after we disabled the forefront the mail flow through without any problem, advise needed urgently. Thanks a lot guys.

Outgoing mail delivery stops working on an Exchange Server 2007 Hub Transport server after you install Forefront Security for Exchange:: http://support.microsoft.com/kb/934286/en-us Anil

Thanks for the reply, but had already checked that both the settings are correct and for your info the mails that in the submission mail queue is internal as well. Thank you.