"Email is simply not secure. Messages are not secure in transit: the protocol used for sending email (SMTP) does not require encrypted connections, so it could easily be intercepted by a third party as travels over the internet. You also have no guarantees about the security of a recipient’s email client or server. A hacker could have surreptitious access to a recipient’s inbox, or curious IT guy could be reading through email on the server."
Unless you encrypt your mail, or host it yourself, you can't really stop things like this from happening. Nobody can set up a perfect hiring process that screens 100% of creeps like this.
