Warning: this will be a fun one I think
I have a client that uses Exchange 2007 for their mail server. I have one user that's at the end of a VPN using Outlook 2010.
Recently, he's getting a situation where he'll contect to Exchange for a few seconds, then get an error, it disconnects, and then reconnects. This happens during syncing (using cached mode with exchange).
Looking at the connection status, it's always on the cache and background tasks. The foreground task never has a problem.
Only error I see in the server event logs is an occasional event that the max number of session objects for MAPI has been reached for this user. I had upped that to 48, which has helped, but now were right back here a few weeks later.
Nothing's really changed for this user in a couple of years, and his e-mail has worked fine till now. Three other users in the same office (also on the end of the VPN) have no issues.
Server is fully patched as is Outlook and the station. I have already investigated the VPN and network to some degree, and adjusted the MTU to avoid packet fragmentation.
I believe it's the result of simply a mailbox that has grown too large; current mailbox size is 5.3GB with approx twenty thousand items in it. But outside of the event log entry on the server, which doesn't match up in frequency with the number of disconnects and re-connects by far, I can't find anythign else wrong.
Any suggestions on how I might pin this down further?