Usually all sites will send a confirmation email and only enable the account if a confirmation link or code from that email is used.
HA, No they don't. Someone started using my gmail address years ago (thinking it was theirs) to create accounts. I have access to so many accounts it's borderline wrong. This person even let their kid sign-up to EA's origin.com and bought a game. I did an account password reset seeing as the email address is mine and now the game belongs to me and they can't play it anymore.
Once I even got digital plane ticket's emailed to me from an Australian airline. I was able to do a password reset and get into the account and do whatever I wanted.
Companies seem to be relying on the "type your email 2 times" method and not the ending an email to verify. It's pretty sad.