You attempted to restore a PST file to the mailbox and the restore failed. This article lists the most common reasons for such failures.

1. The PST file exceeds the mailbox limit.

We recommend that you disable all storage limits for mailboxes you are going to import PST files to. To change mailbox limits, navigate to the Services > Mailboxes > Disk Quota Management page and click the Manage Individual Mailboxes button. Read the Knowledge Base article on How To Use Storage Management On Exchange Account for more information.

2. The PST file is password-protected.

If the PST file is password-protected, Outlook Backup cannot open it to start importing messages.

To verify that the file is not password protected, open the file in Outlook:

Open Outlook, navigate to File > Open & Export > Open Outlook Data File. Browse to find the file and click Open.  


  • If the PST file is password protected, you will be prompted to enter the password.
  • If the file is not password protected, its content will appear under the Personal Folders top-level folder in the Outlook profile.

3. The PST file is corrupt or the upload was incomplete.

  • Run the scanpst.exe tool to repair the PST file and try to upload the file again. This tool will scan your file for errors and recover corrupt items if possible.
    Read the Knowledge Base article on How To Use The Inbox Repair Tool (scanpst.exe) for more information on this tool.