As much as you protest this people will still do this. Coincidentally, this is why I have a separate email address for any site that anyone may look down upon.

As much as you protest this people will still do this. Coincidentally, this is why I have a separate email address for any site that anyone may look down upon. Figuring out what sort of services you sign up for online is usually as trivial as trying to sign up a new account with your email address. This is also why if my site enforces 1 user per email address, I make sure I do that check only if all other information is valid. In comparison, most sites let you enter a bunch of invalid information but a valid email address and will happily let you know that person already has an account. If you have to enter fully valid information, theres some risk you will sign the user up and let them know someone is using their email address for things.