Add Blocking in Entra

Blocking SPAM

Within O365 Admin Center > Click "Show pinned"

Click Security

Click "Email & collaboration"

Click "Policies & rules"

Click Threat Policies

Click Tenant Allow/Block Lists

Click "Add"

Click Block

Type @xxx.xxx to Add domains & addresses

Select dropdown under "Remove block entry after" Select Never Expire

Paste ticket link in Optional note section

Click "Add" (This completes block process)