When you send me e-mail using my little contact form, I need to get your e-mail address for two reasons:
1) It cuts down on the nasty little spam robots who try to use my form to junk up my inbox.
2) It wouldn't be any fun if I couldn't reply to your message to say, "Thanks!" or, "So's your old man!" -- You know, that sort of thing.
So, other than replying to your message and to any subsequent replies you might make to my own thoughtful first reply, I hereby solemnly promise never to use your e-mail address for any other purpose, and never EVER to give it to anyone else for any reason whatsoever without your explicit permission.