Microsoft Outlook

Outlook.pst and file locking

Microsoft Outlook locks the PST files that contain your messages.  One possible error message is "Outlook.pst will not backup as: the process cannot access the file because another process has locked a portion of the file."  These locks can remain even if you don't have an Outlook window open.

The solution is to log in as a different user, or even restart the computer and log in as a different user to clear the file lock.

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If you're restoring a backup of Outlook.pst and the copy fails because of a lock but corrupts the Outlook.pst file, you can avoid this by having Beyond Compare detect partial file locks:

  1. In the Folder Viewer, select Session | Comparison Control and pick the Advanced tab.
  2. In the Miscellaneous group, enable the Detect partial file locks option.

Synchronizing Outlook Email Messages

Beyond Compare doesn't provide a method to synchronize email messages between installations of Outlook.  However, there are dedicated utilities for this purpose.  The Outlook synchronizing tool most recommended by our users is SynchPST.  For a long list of Outlook synchronizing tools, see the Synchronizing Microsoft Outlook on two machines page at

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