Mail.app inbox becomes blank after a few minutes of use On a newly installed and fully updated Mountain Lion system, I see the following problem:

After a few minutes of using Mail.app (or even just letting it sit in the dock), the inbox becomes empty.  More precisely, the inbox of an Exchange mail account becomes empty.  If I let the program sit in the dock, I receive new mail notifications, but I can't read the messages because the inbox looks empty.

Restarting Mail.app is a temporary fix, but the problem will come back in a few minutes.

Has anyone seen this problem?  Are there any solutions?  I did not do anything special which could have caused this and my inbox is small (less than 100 MB---I did read that this can happen when the inbox is too large)
Is your exchange environment hosted? Office 365 perhaps? 

My mailbox occasionally does exactly what you describe. This was a known issue in ML, I would expect a fix at some point, but for now here are the few steps that I take that fixes it for awhile.None of this seems to be a "permanent" fix, but should last a bit longer.


Select the folder in Mail that is missing items.
Select "Mailbox"
Select "Rebuild" from the bottom of the menu.


OR...

You can rebuild the Envelope-Index by throwing it away, it's located at ~/Library/Mail/V2/MailData/


Your Library folder is hidden by default. Select Finder (in the dock) > “Go to Folder” and then enter “~/Library.”
In ~/Library/Mail/V2/MailData, delete any file that begins with “Envelope Index,” such as Envelope Index or Envelope Index-shm.
Mail will rebuild the Envelope index when it is reopened. It will take a few minutes to rebuild the entire index.


If you're using Office 365, I've had more success by disabling the "Use Auto-Discover service" on those mail clients that are misbehaving.