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)

2 Answers 2


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.

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


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

  1. Your Library folder is hidden by default. Select Finder (in the dock) > “Go to Folder” and then enter “~/Library.”

  2. In ~/Library/Mail/V2/MailData, delete any file that begins with “Envelope Index,” such as Envelope Index or Envelope Index-shm.

  3. 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.

  • Thank you very much for registering just to post this! It's a university account, I am not exactly sure how it's set up (I only know that Mail told me it's an Exchange account). I did Rebuild thing already, I found it on some website. It only lasted for a couple of hours. Now I have removed some related certificates from Keychain based on another website which said that this didn't fix the problem (but I thought it was worth a try), and it's been working for about one hour. I'll try your other two suggestions when/if it stops working again.
    – Szabolcs
    Commented Nov 28, 2012 at 21:03
  • This is a great answer - I would just add make a full back up of your Mac before rebuilding anything you can't afford to lose. That goes for iPhoto library databases, aperture, Mail, whatever. Sometimes little glitches like these are all the warning you get that the hard drive is soon to become more problematic.
    – bmike
    Commented Nov 28, 2012 at 21:18
  • I see. You can tell if it's Office 365 by the address of the mailbox host. In the Account preferences (within Mail) the address will be something like bnXXXX.outlook.com.
    – dpauken
    Commented Nov 29, 2012 at 14:00
  • Out of curiosity, how long has this problem existed? Since ML came out? I'm rebuilding from time to time to keep it usable, but it's probably going to be easier to just switch to another email client ... Thanks for the answer again, it was very useful!
    – Szabolcs
    Commented Dec 3, 2012 at 0:25
  • In my case, ML was released at almost the exact same time as our Office 365 migration, so sadly, I may never know if it would have been any different on our own exchange box.
    – dpauken
    Commented Dec 3, 2012 at 6:29

That's an odd symptom, but troubleshooting Mail is fairly easy.

You can disconnect from the network and start the program. That isolates it from any server influence and you can see if messages draw and are downloaded. Next, you can run the connection doctor and the activity window (search for both from Mail's help menu) and most issues are quickly sorted with these two tools to show what is happening behind the scenes.

If that doesn't work, you can post a follow on or edit this to clarify what specifically is tripped up in this case. Hopefully it's a download issue where the client hasn't gotten a good message yet (and only downloaded the mail envelopes / subject and the presence of a message - but not the body of the messages).

  • Thanks for the answer. It's been working for the past hour (see my other comment), but I'll try your suggestions when/if it breaks (it usually does---I removed and re-added the account several times now).
    – Szabolcs
    Commented Nov 28, 2012 at 21:04

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