How and when to disable Outlook PSTs

How and When to Disable Outlook PSTs


If you’re still supporting Microsoft Outlook PST files in your environment (or believe you don’t have them anymore and want to make sure…) and need to disable them so they don’t boomerang back, here are some easy steps with the right timing to perform this smoothly with the least impact on your staff:

DISCLAIMER: Please test, test, test first! Outlook PST files have been around since 1997 (!!!) and are still in use, though many users aren’t aware that they have them, and many IT organizations are surprised to find them when they run inventories…

Step #1

If needed, instruct your users to remove any Outlook rules that move messages or interact with their PST files. This helps to avoid error messages, helpdesk calls, and IT surprises ;)

Step #2

Set this GPO to prevent users from adding new content to existing PST files

This setting effectively renders PSTs “read-only” and prevents them from increasing in size, though PST files can still be opened and attached to Outlook.

Registry Hive     HKEY_CURRENT_USER

Registry Path     software\policies\microsoft\office\16.0\outlook\pst

Value Name       pstdisablegrow

Value Type         REG_DWORD

Value     0             Disabled (default)

Value     1             Enabled (adding new content is disabled)

  • Once deployed and active, now is the time to migrate the PSTs to retain and protect their data.

Step #3

When the PSTs are migrated or removed from your environment, you can now prevent users from adding PST files to Outlook with this GPO setting:

Registry Hive     HKEY_CURRENT_USER

Registry Path     software\policies\microsoft\office\16.0\outlook

Value Name       disablepst

Value Type         REG_DWORD

Value     0             PSTs are allowed (default)

Value     1             No PST files can be added

Value     2             Only Sharing-Exclusive PSTs can be added

  • If SharePoint lists or Internet Calendars are used within your environment, the value of 2 will allow these but no other PSTs to be used.
  • These GPO settings are compatible with Outlook 2016 and newer versions


Prevent future PST file use by applying these settings to all Outlook users as part of your standard policies going forward. For ease of administration, the Microsoft Office 2016 and higher administrative ADMX template files can be found here -