create spam filter or rule based on the TLD

I'd like to mark emails from certain TLD's as spam or junk. For example:

stanley_giveaway_days@marketing.cacophonex.bet

AND

michael.stanley_giveaway_days@cacophonex.bet

I presume I should use a regex filter for this, but I cannot find a reference to test ONLY the TLD portion - regardless of the number of subdomains in the address.

TIA