By default, the DLP Add-in for Outlook should be enabled and running after enabling Data Loss Prevention and configuring DLP policies on the agent machine. If it is not enabled and the issue persists after verifying the Data Loss Prevention on the Agent side, proceed with the troubleshooting steps below:

1. Copy the code below box into Notepad, and save it as 'DLPAddin.reg'. The file is also available for download here: DLPAddin.reg

   Windows Registry Editor Version 5.00

   [HKEY_LOCAL_MACHINE\Software\Microsoft\Office\Outlook\Addins\TmDlpExAddin.Connect]

   "FriendlyName"="TrendMicro DLP Addin for Outlook"

   "LoadBehavior"=dword:00000003

2. Import/Manually add the registry key.
3. Ensure the registry key is present in RegEdit.
4. Right-click on TmDlpExAddin.Connect folder.
5. Select Permissions...
6. Click on Advanced.
7. Remove "SYSTEM" from Permission Entries.
    

   May need to disable inheritance. In that case, it is recommended that explicit permissions be granted rather than removing all permissions.

    
8. Click Save.
9. Restart the system and see if the registry key changed again.

   In some cases, adding the key in HKEY_LOCAL_MACHINE worked, whereas adding in HKEY_CURRENT_USER did not.

10. If TrendMicro DLP Add-in for Outlook is shown in the Inactive Application Add-ins part, the following steps may be used to enable it:
    1. Use Script for Enable/Disable DLP Outlook Plugin to enable DLP plug-in. Run it as administrator. (Unzip password: novirus) and restart Outlook. EnableDisable_Outlook_Addin.ZIP

       After that, TrendMicro DLP add-in for Outlook should be seen under the Active Application Add-ins part.

       

    2. If TrendMicro DLP Add-in for Outlook still appears in the Inactive Application Add-ins section after running the script, use the "Go" button in the Manage section to enable it. Restart outlook to make the setting work.