If you've ever run a website that doesn't verify email addresses, you will likely run into this problem. The average person doesn't double check for typos, and

If you've ever run a website that doesn't verify email addresses, you will likely run into this problem. The average person doesn't double check for typos, and they can't discover it after the fact because they didn't notice the typo in the first place, and you won't be able to contact them to inform them. Your suggestion of disabling copy instead of paste may be a better solution, though.