What do you do when you don’t trust your employees or the people they choose to give their email addresses to? In the case of WatsonWyatt, you tell them they are bad people, who use unacceptable language.
I used to run web-based forums 7-8 years ago, and we originally tried to filter swear words, but in the funny way that humans do, people were smart about getting around those filters. We eventually gave up and when the game went away, people didn’t really swear all that much, and when they did, we realized it didn’t really matter.
It turns out, people swear even in real life!