email confirmation script

Hi, I'm trying to find a script that does the following: 1. A user is presented with a form with a textbox for their e-mail address. 2. The user types in their e-mail addrees and submits the form. 3. A note is then sent from that server if their e-mail address , in fact, exists. 3. If the e-mail address does exist - the user receives a note. The user is then presented with a link which they click to confirm and their e-mail address in then inserted into the database. I've searched through google for: e-mail, confirmation, php, etc. and have not come up with anything. If anyone has code that I could look at, I would greatly appreciate it. Many thanks, Tony Ritter