05-02-12: Operatenore
I believe, though, there was something of a misinferrence regarding member Tholt's post, or a misimplication: C'list allows one to flag a post/offering (of goods/services) that one deems to be fraudulent...(?) (that's a whole 'nother can of worms other than the obviously redundant/prostitutional/"other" categories. There is no way, in my most recent experience - as most people are contacted through their hidden emails - that one can alert C'list to warrantedly fraudulent contacts (someone please correct me if things have changed in the last several weeks...)
Operatenore, there is indeed a way via a link on the Craigslist generated emails to flag the responder as spam. Perhaps this is a recent addition. I used it a couple times on an item I had for sale within the past few weeks.