Here are a couple of good (and complicated) tools that you can use to troubleshoot mailbox and outlook related issues:
Microsoft Exchange Server MAPI Editor (MFCMAPI)
MFCMAPI uses Microsoft's published APIs to provide access to MAPI stores through a graphical user interface. Its purpose is to facilitate investigation of Exchange and Outlook issues and to provide developers with a canonical sample for MAPI development.
Microsoft Exchange Server Information Store Viewer (MDBVU32)
Use Information Store Viewer (also called MDBVu32) to view or set details about a user’s message storage files, which consist of the private information store, the personal folder file (.Pst), the public store and the offline folder file (.Ost). The Information Store Viewer shows the properties available for each message, how you can use them, and in what format they appear.