Enable this policy to prevent indexing of any Microsoft Outlook items. The default is to automatically index Outlook items. If this policy is enabled then the user’s Outlook items will not be added to the index and the user will not see them in search results.

1. Registry path is:

   HKEY_LOCAL_MACHINE -> SOFTWARE -> Policies -> Microsoft -> Windows -> Windows Search # PreventIndexingOutlook

2. The Administrative Template path is:

   Windows Components -> Search

* Making mistakes while changing registry values can affect your system adversely. We recommend you to create a System Restore point before making registry manipulation. If you're new to Registry Editor, read this beginner's guide.

** To locate the registry and administrative template path, checkout beginner's guide.