Mailgun has an API endpoint that works pretty well. If you enter "foo@gnail.con", it suggests "foo@gmail.com". It's overkill for an HN registration form, where

Mailgun has an API endpoint that works pretty well. If you enter "foo@gnail.con", it suggests "foo@gmail.com". It's overkill for an HN registration form, where if I type my email wrong, I can just re-register, but for checkout forms it can be worth putting in a little extra validation.