I wonder if it's really necessary to provide an unlink mail button. If the user decides not to register, then an account is not created. They can simply abandon

I wonder if it's really necessary to provide an unlink mail button. If the user decides not to register, then an account is not created. They can simply abandon the registration process and forget about the service. Unless the service sends out regular email reminders or something to anyone who has entered their email address, then I can understand the need for an unsubscribe link.