If they had a permanent fix every mmo that had this issue they would have already implemented it and be done with rmt spam, unfortunately their isn't a simple fix without it effecting of others legit players who don't spam in tells or shouts. They would have to restrict almost every word that would be related to selling/buying in that regard that allot of words that legit players use in common conversations not even related to selling or buying if you think about it. It would restrict us from actually talking because I can't use XXX word and doesn't get sent or seen by you or friend it would be the equivalent of not being able to send a tell to someone while in a dungeon or out of dungeon.