1. In the Windows Client Configuration Policy, select Content Tracking.
2. Select Whitelisted Processes.
3. Set the following allow list for Outlook.exe:
   
   NOTE: Set the following path for both case sensitive and lowercase, as shown in the examples below, and select both of the options for All Files and File.
   
   %LOCALAPPDATA%\microsoft\windows\inetcache\content.outlook
   %LOCALAPPDATA%\Microsoft\Windows\INetCache\Content.Outlook
   
   %USERPROFILE%\AppData\Local\Microsoft\Windows\INetCache\Content.Outlook
   %USERPROFILE%\appdata\local\microsoft\windows\inetCache\content.outlook

​NOTE: The temporary files or temporary secure folders that contain monitored files are rescanned. The Temporary Internet Files folder is stored on a server where the user might have insufficient permissions. When you open attachments that are considered safe, Outlook puts them in a subdirectory of the Temporary Internet Files directory as a precaution.

The DLP Outlook Add-in preserves content fingerprints in an attachment when it sends or receives an email. This action can briefly consume system resources if the attachments contain a large amount of text.

To disable this action, perform the following steps in the Windows Client Configuration Policy:

1. In the Windows Client Configuration Policy, select Content Tracking.
2. Select Content Fingerprinting for Outlook.
3. Deselect the Preserve content fingerprints in attachments when sending or receiving an email option.