From the Warhammer Online Herald - the following is pretty much what I had been wanting to see from them rather than the re-active "after they've already spammed me" solution:
In the continuing fight against enemies of the realms (AKA: Gold Sellers) a new tool has been brought to our attention. The third party add-on “Spam Me Not” will “intelligently detect, block and reports commercial and annoying spam messages before you even see them, without relying on an extensive list of blacklisted domain names”.
While this is not an “official” Mythic product nor is it supported or endorsed by Mythic, it can be a valuable resource in helping to make your online experience more enjoyable.
“Spam Me Not” v 0.2 BETA can be found here.
As always we encourage players to continue using the in-game tools provided to you to report potential violators. Thanks for your continued support.