Enable/disable backups of OST and OAB files [Microsoft Outlook OST Files Missing from Backup]

Written By Tami Sutcliffe (Super Administrator)

Updated at April 21st, 2022

By default, Microsoft creates a registry key that forces Windows Volume Shadow Copy services to exclude Outlook OST and OAB files from the backup.  When this default behavior is enabled, the backup agent will not capture such files as part of the backup. 

In most cases, this is perfectly acceptable behavior, as OST and OAB files are purely cached data that will be rebuilt automatically by the Outlook client after a system recovery is performed.  

For the rare case where it is required to capture OST files in the backup, the Windows Registry can be modified to remove this restriction.  

Enable Backup of OST and OAB Files 

To enable backups of OST and OAB files, download and apply this registry patch onto the affected protected system: 

 Enable  [This will download as a .txt file] 

Disable Backup of OST and OAB Files

Backups of OST and OAB files are disabled by default.  If you have previously applied the registry patch above to enable such backups, and wish to disable backups again, download and apply this registry patch on the affected protected system:

 Disable  [This will download as a .txt file] 

NOTE: To apply the registry patches referenced above: 

1. First,  download and save the linked .txt file to the affected protected system.

2. Ensure that the 'view file extensions' options of Windows Explorer is enabled so that you can see the .txt extension of the downloaded file.

3. Rename the file with an extension of .reg instead of .txt so that Windows will understand that the file is a collection of Registry settings.

4. Once the file has been renamed, simply open the file by double-clicking it, or right-click and choose Open. Windows Registry Editor will open the file and prompt you to import the registry values.


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