Many spammers use foreign emails to bypass filters or to cause confusion with legit domains (yahoo.com vs. yahoo.com.jp).
MW needs a filter option that has a checklist for the hundred other TLDs for countries that would never be a source of legitimate emails. There is no reason for me to get emails from Russia, east European countries, Africa, or many Asian countries. I would simply check the list of TLDs and ban emails that contain a .po, .jp, or whatever. The list would include the full name of the country to avoid confusion: .jp - Japan.
