We apologize for the delay in response. If you are in the Classic View in your workspace email, you should go to your "Settings" menu and choose "Spam Settings". There you can go to the "Blocked List" tab and set a filter for domain names only (ex: thisdomain.us). You will not be able to block by TLD only. However, if you go to the "Custom Filters" tab, you can create a "From" filter that contains the .TLD to reroute emails from such an address. You can send them to Bulk Mail or Trash.
Supporting you at x.co/247support