It's pretty unlikely Jacqui - there are far easier ways to get email addresses than that. On CBF, not only would someone have to email you via the forum, but you would have to reply to them for them to even see your email address. There are far more efficient ways to reek havoc than that.
Sadly it's just one of those things. I was reading about someone who set up new unique email addresses so they could track what happened to them. They were only used once each ever, to join mailing lists on very reputable sites - blue chip UK companies. It was amazing to learn that emails from totally unrelated companies and spam emails started arriving. So it seems you never know who is selling on your email address.
Definitely never cuddly old CBF though, I promise.