I have a weird bug/misconfiguration/curse that's been chasing us around for a couple of months. Our current set up is an Exchange Server 2007 on Windows Server 2003R2 with Outlook 2010 on Windows 7 as our client.
Every couple of weeks or so, Exchange/Outlook start to lock up when sending Emails. Emails will get stuck in the Outbox on Outlook and will require a restart of Outlook to unlock them. In the meantime OWA has no issues with the mail leaving the Outbox. All of our phones/devices have no issues sending either. This occurs only with Outlook.
We have run the mail flow troubleshooter, examined error logs, and we still can't track this down. The maddening thing about this as well, is that it only lasts a few days then quietly disappears. Then a few weeks later it will show back up again.
We have run netmon on the clients, examined the rpc diagnostics, and we still have no idea what is going on.
Any suggestions on things to look at on the server side or client?