These instructions were created and tested using Active Directory Server 2008 R2 and Office 2010 32-bit.
Download the Office 2010 ADM files from http://www.microsoft.com/en-gb/download/details.aspx?id=18968
Run and extract the files to a temporary location
In Group Policy Management, create a new GPO and link it to the OU which contains the users who we want to prevent creating/amending PST files.
Expand User Configuration > Policies.
Right click Administrative Templates: Policy Definitions (ADMX files) and select Add/Remove Templates
Browse to the extracted files in the temporary location > ADM > Outlk14.adm (add any other ADM files if required for other policies)
Expand Microsoft Outlook 2010 > Miscellaneous > PST Settings.
Set the following policies:
Prevent users from adding PST’s to Outlook Profiles and/or Prevent using Sharing-Exclusive PST’s – Set to Enabled and select ‘No PST’s can be added’
Prevent users from adding new content to existing PST files – set to Enabled