Please put filters for keywords for the /chat and /tell sections.
You already put filters on profanity and we can unclick that if we want to. Here are some great filters that you can add: "www", "WWW", "USD", "US_D", "com", "Fast Delivery", "c0m". You can use code that will substring every sentence and then lower case all the words so that caps does not matter if used.

Another way to slow down the spamming is to put a function that when a character shouts more than x number of times in a given time limit, it blocks all shouts from that one person for x minutes. GW2 has this feature. Because, in the cities, people are spamming RMT every second of the day. I don't really know how they are doing that for you can only put up to 15 lines of code in a user micro. But that is beside the point.