how to send user email confirmation without register the user

I want the new user on resgistration to receive a confirmation email, and only after confirm the email can get access to the login area, not before.

I had made a custom form, a new table to store the info, send the email of validation, in the meanwhile the user is only with his info on a custom table on the database, only after the email validation, this means the user click the custom email link and a new window is open on the website congratulating him for the new registration and email validation, and the user gets registrated, already log on and goes to the home page. in the backend wordpress validates the key generated and returned by the user, regist the user and delete the info from the custom email confirmation table. ok, this is all done and working fine. eheh.

My question is is there any wordpress function to do the same, because I dont know any.