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.