25. March 2013 · Comments Off on How can I stop users from using PST files · Categories: Microsoft · Tags: , , ,

PST files are a burden in many environments. They’re hard to manage, hard to perform discovery on, and prone to loss when stored on local machines. Many companies now use archiving solutions at the mail server, such as the Exchange 2010 archiving functionality, to avoid the need for user PST files.

Briefly, these are some of the problems with PST files:

  • Microsoft does not support using PST files over a LAN or WAN network (KB267019). Using PST files located on network shares can slow down Outlook and can cause corruption of the PST file.
  • Anti-virus countermeasures cannot be implemented on PST files as easily as Exchange Server mailbox databases.
  • It is difficult to accurately report on PST file use, making reporting on organizational mail storage and planning for future growth difficult.
  • Managing content of PST files is difficult.  Exchange Server provides tools to manage the content of mailboxes (such as Messaging Records Management) and to export or remove data from mailboxes (such as the Export-Mailbox cmdlet) but there are no such tools to manage the content of PST files.
  • Local PST files are difficult to back up, making them vulnerable to data loss.

To phase out PST files, take a two phase approach. First, you can stop users from writing to PST files but still allow them to read from then. You can then totally block PST files.
You make these changes using two policy settings that are found in the Outlook Group Policy template under User Configuration, Policies, Administrative Templates, Microsoft Outlook <version number> Miscellaneous, PST Settings. The settings are called Prevent users from adding new content to existing PST files and Prevent users from adding PSTs to Outlook profiles and/or prevent using Sharing-Exclusive PSTs.

If you don’t want to use Group Policy, you can achieve the same result using registry changes. The keys are found under

HKEY_CURRENT_USERSoftwarePoliciesMicrosoftOffice<version, e.g. 12.0 or 14.0>Outlook (set value DisablePST to 1 to disable the use of PSTs)


HKEY_CURRENT_USERSoftwarePoliciesMicrosoftOffice<version, e.g. 12.0 or 14.0>OutlookPST (set value PstDisableGrow to 1 to disable writing to PSTs).

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