If Outlook is installed on the system, configure the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Search -> "Enable indexing uncached Exchange folders" to "Disabled". Value Name: PreventIndexingUncachedExchangeFolders Here is the tutorial: Step 1: Open the Outlook application and then click File > Options > Search. Registry Path: \SOFTWARE\Policies\Microsoft\Windows\Windows Search\ You can also use the Outlook index repair menu option to rebuild the Outlook index. For checking the Indexing Status in Outlook application, follow below steps: Launch Outlook 2016. Make sure of whether a specific Outlook file type is left from indexing or not. If Outlook is installed on the system and the following registry value does not exist or is not configured as specified, this is a finding: If you are missing emails when searching in Outlook 2016 and you know they should be there it could be a problem with indexing or with your exchange offline. Check the indexing status in Outlook, before we jump to the methods for fixing the search problem. Navigate to File menu, click on Options and select the Search option on the left panel. Follow the given instructions one-by-one: Run your Outlook application. If Outlook is not installed on the system, this is NA. If the above solutions are not working, users can try rebuilding the Outlook Search Index as it can help resolve the issue. Make sure that it is set to Not Configured, not working or Disabled option. Windows Vista Security Technical Implementation Guide Now, run gpedit.msc from Run command to open the Local Group Policy Editor and follow the below-mentioned setting: From the right-hand side, you can see the Prevent indexing Microsoft Office Outlook. This setting prevents mail items in a Microsoft Exchange folder from being indexed when Outlook is running in uncached mode. Indexing of encrypted items may expose sensitive data.