[JeroenRansijn]

I understand your reaction, but this is basically a backdoor for checking if e-mail accounts exist, and could be misused by serious attacks. I'm only exposing it.

[ternaryoperator]

You expose a hole by contacting the company and letting them know so they can fix it. You don't use the hole to dick with their site.

[dromidas]

It could be worse. He could have gone and generated every possible email [e-mail] [e-mail] [e-mail], etc etc. And unsubscribed them all, stored their email addresses, and then subscribed them all to fox news newsletter.