Microsoft Outlook Inbox Repair Tool (Scanpst.exe) allows you to recover emails, folders and other email items from a damaged Personal Folders file. Scanpst.exe is a hidden file that comes with Windows installation. The tool validates and fixes corruption errors that are associated with a .pst file. It corrects errors that exist in internal data structures of Outlook data file, but can fail if the corruption is severe. The tool also has a limitation that it cannot repair a file of more than 2 GB in size in Outlook 2002 or earlier versions. To deal with problems when the tool cannot repair your damaged .pst file, it is recommended to use third-party Outlook Inbox Repair tools that can repair the file using more powerful scanning procedures.

To illustrate the scenarios when the Scanpst.exe tool can fail, consider a situation when your .pst file gets corrupt:

1. 
   You receive an error suggesting that the message interface has returned an unknown error.
   
2. 
   You try to repair the file using Scanpst.exe tool.
   
3. 
   The scanning process results that there are errors in the file. But when you click to repair them, the application hangs and you cannot repair the file.
   

Cause

The probable causes are that PST file is oversized, larger than 2 GB. This occurs when you use Outlook 2002 or an earlier version file.

The Scanpst.exe tool can also fail to repair if corruption extent is beyond its repair capabilities.

Solution

Following solutions can help you recovering from such problems:

1. 
   To repair an oversized file using Scanpst.exe tool, you can first crop it by using PST crop tool. This will reduce the size of the file by truncating it. It is highly suggested to backup the file prior truncating it. Some of your important emails might get deleted.
   
2. 
   If you can open the file, you can reduce the file size by deleting the unwanted emails and items
   
3. 
   If the problem persists, you should use commercial Inbox Repair Tool for your damaged .pst file. These software provide you graphically rich interface plus efficient Inbox Repair Tool capabilities to repair even a highly damaged file.
   

Stellar Phoenix Outlook PST Repair is an advanced and fast utility that scans and repairs a corrupted .pst file using high-end scanning procedures. The Stellar's Inbox Repair Tool is compatible with Outlook 2007, 2003, 2002 and 2000. It is a safe .pst file repair product giving 3-pane structure to view the email messages. The software can restore all file items at a safe location.