Are you sure that the "well known server" was genuine. Spammers gain real email addresses by sending mails like that to random email addresses. If they receive an answer, that proves that the email address is live and is added to spammers' databases.
You should never, ever reply by clicking a link on the email you are sent; if you want to reply, you should always go to the site yourself and find a "Contact us" link or email abuse@ which often works.
In the case you quote, if it was genuine, a simple failure to reply would have cancelled the application.