If you furnish your email address when someone on a message board requests it, please be aware that a semi-skilled hacker can obtain significant amounts of information about you from that email address. Personally, I would NEVER send an email address (even something like a Yahoo or other secondary address that you think is anonymous) to someone who posts publicly on a message board, soliciting that address from anyone who will send it.

It's different if you want to correspond with someone that you "know" and think you can trust after a history of communication on a message board. But just providing it to someone who posts publicly asking for it -- you're inviting trouble.