Don't bother emailing the person who posted your copied content. Obviously, they're clueless.
Instead, do a whois search on their domain name, and find the name of their web hosting company. Go to the hosting company's web site, and file a DMCA complaint. You can usually find their process for this by checking the Terms of Service, which often contains the email address for copyright issues, or a form you can fill out.
Most hosting companies take copyright complaints seriously, and will either remove the content themselves, or send a message to their client telling them to remove it, or lose their service.