I say we do the EVE Online thing - give us the option to tax people gil for sending a /tell before we read it, and then give them the option to either pay or not send the tell at all. We wouldn't actually receive the gil, to prevent abuse, but losing all the extra currency would be absolute hell on their business model.

An easier solution would be to implement a filter that doesn't just look for plaintext keywords - changing an o into a 0, or a W into those... weird Wish shapes that have sprung up recently, shouldn't foil a filter made by a competent programmer. Making it too difficult to actually say the URL of the website might be the best option in the long run, not banning anyone who says 'life is acceptable' all the time. Multiple passes should be done as well - the message seems legit? What about with all punctuation and symbols cut out?