Create login procedure...

Hello, I change the procedure to create an account for users. For the moment, the user (to create and log in), have to create an account with e-mail + password. I'd like to create a procedure to check the e-mail (login) validity. But I'd like to check if the e-mail used exist or not. The procedure, I'd like implement : 1. User create new account (enter : fisrt name, last name, e-mail, password, ....) 2. An e-mail is send to user to check if e-mail exist. In the e-mail, my first idea is to send with an auto-generated number 3. User have to join a specific page to enter the auto-generated number to check the validity. My question are : 1. What do you think about this procedure ? your advise, idea are welcome 2. Is it possible with mySQL to delete user after for example 2 days, if the user not confirm the subscription ? Bye