I'm wanting to either let users login with either Facebook or their email address. If a user wants to use their email, should I verify that they are indeed the owner of that email by sending a confirmation code? I've seen apps such as Snapchat don't verify if you're the owner of that email or not, which causes me to believe someone else could use your email as their account login without your knowledge. What would be the proper way to handle registration via email? Thank you!