Blizzard did not, it was an open source program that is the biggest weapon against rmt spam. There are a few in use my favorite was a program called "Bad Boy", it works by screening all incoming chat for key words, symbols, and general quality. It then automatically blocks the message, and reports the sender preventing you from ever knowing you got the message. There are also in game things like the ability to restrict messages from persons below a certain level, chat frequency limiters, and the in ability to share web addresses.