Kicksend has a library for that: https://github.com/kicksend/mailcheck https://github.com/kicksend/mailcheck I actually think that this library functions as a

Kicksend has a library for that: https://github.com/kicksend/mailcheck https://github.com/kicksend/mailcheck I actually think that this library functions as a really great client-side validation that won't get you tripped up in trying to be RFC compliant. There's really not anything more that I'd do aside from sending that blessed confirmation email.