When you use the Microsoft Office 365 Import service, you may want to control whether users can add new items to .pst files and how users use .pst files in Microsoft Outlook. This article describes how to prevent users from adding new items to an existing .pst file and how to prevent users from creating new .pst files during the import process.
Important Follow the steps in this article carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.
Note The <x>.0 placeholder represents the version of Outlook: for example, 15.0 is Outlook 2013, 14.0 is Outlook 2010, and 12.0 is Outlook 2007.
On the Edit menu, point to New, and then click DWORD Value.
Type DisablePST, and then press Enter.
Right-click the DisablePST registry entry that you created, and then click Modify.
In the Value data box, type 1, and then click OK.
Note The DisablePST registry entry can be set to the following values:
Users can add .pst files. This is the default value.
Users cannot add .pst files. However, in scenarios where a .pst file was connected to Outlook before this registry value was added, the existing .pst file will still be connected. No new.pst files can be added.
Users can only add exclusive sharing .pst files, such as SharePoint .pst files.