Exchange 2010 on an SBS 2011 server, starting a few days ago, the transport DB mail.que is growing to ~5GB at which time the Exchange transport moves the Queue folder contents to a subfolder Queue.old and proceeds again with rapid expansion of the mail.que file, along with ~1,000 .log files. The Transport service will steadily increase in CPU and Memory usage. Once the mail.que file hits ~ 5GB the second time, the service stops. The service does however change status in services.msc, to blank. I disable the service and reboot the server, rename the Queue folder, restart the transport service and the cycle starts over. The entire cycle of events takes 1 - 2 hours to complete.
During the time that the Transport services is running, mail moves in and out, running a Get-Queue at various times during the 1-2 hours shows mail moving through without issue the queue is empty most of the time once it processes through the stacked up messages from being down.
Following are the items attempted/addressed so far, in chronological order:
Verified no AV is loaded or scanning now.
Verified Drive space is no issue
Mail.que stops growing when transport service is stopped.
Edited the Edgetransport.config to move the QueueDatabasePath and QueueDatabaseLoggingPath to another partition.
Downloaded and Scanned the system with Malwarebytes, no issues found, uninstalled.
I am familiar in Exchange Admin but not an expert by any means.