We have a relatively new Exchange Server 2003 (Entpr) running on Win2003 (Entpr) in a Win2003 domain. The Exchange server is not a DC but does have Sophos Enterprise Server installed, running Pure Message and Antivirus. We have a little less than 100 users and the Exchange Server is well over spec'd for its current chores.
The mail has been running without problem for about 3 months since we installed Exchange, however last week it developed a problem. All the Outlook MAPI and OWA clients could apparently connect and send mail however none was being delivered.
On investigation we found that all the mail was just sitting in the Messages Pending Submission queue, with no unusual errors in the event log. A reboot shifted the queue ok but since then the problem has re-occurred a couple of times a day.
As a short-term fix we are stopping the inetinfo.exe process to shift the queue, which saves a reboot, but are no closer to finding the actual problem.
Any ideas would be very welcome??