Lately, I have been inundated with spam and setting Rules has not helped. I finally seemed to have solved the problem after I realized that most of the sender's emails ended with .de Consequently, I set up a rule to delete any email that contains .de in the From field, and it seems to be working. I assume that de refers to Germany (Deutschland). I have also received emails ending in .es which I assume is Estonia.
I did some research and .es is Spain (EspaƱa). As it turns out, Estonia is .ee