In the Microsoft Defender portal at https://security.microsoft.com, go to Email & collaboration > Review > Restricted entities. Or, to go directly to the Restricted entities page, use https://security.microsoft.com/restrictedentities.
On the Restricted
1. Open the Registry Editor
First, close your MS Outlook.
Now, open Run dialog box. For this, press Win+R, type regedit, and click OK.
Figure 1: Run-regedit-command
2. Find the