I once emailed Daniel Bernstein and received this fun reply before my email was let through: Professor Bernstein has asked me to reject all bulk mail messages.

I once emailed Daniel Bernstein and received this fun reply before my email was let through: Professor Bernstein has asked me to reject all bulk mail messages. But I'm a rather primitive computer program, and I'm not sure whether your message is bulk mail. If you reply to this notice, you are (1) acknowledging that Professor Bernstein does not want to receive bulk mail; (2) confirming that your message is not part of a bulk mailing; and (3) agreeing to pay Professor Bernstein $250 if your message is part of a bulk mailing. I won't look at the contents of your reply. A simple OK is fine, as long as it's sent to the address shown above. Lets just say knowing his history, I probably wouldn't spam the man. (I didn't get a reply, btw).