Unfortunately this is broken just like all other attempts I've ever seen.

If this is true: http://i.snag.gy/RSwiG.jpg

Then explain why the e-mail is arriving: http://i.snag.gy/gWPn5.jpg

Sure this is an extreme edge-case, but this was my second test. Who knows what else it rejects. Actually, why do we validate email addresses anyway? Whynot just try and send that validation email that you're going to send anyway? And on top of that, why would I ever trust a free third party service to check all my user's addresses?