When you receive a mail like that simply don't reply and do remove (or change) the topic. If you reply they can build a case on that since there in actual contact with the one behind the website. And you are spreading around warez which is illegal in most countries. Make sure you are hosted in a country where it is in the Grey area at least.

Even thought you are online and we are not robbing a bank, killing people ( Well ak47 does) you are still doing something illegal in there eyes, and in the actual law. Don't go around mailing them to suck your dick and swallow the load.

Most likely nothing will happen, but if they do make a case on your website they can bring up all the mails you have sent. Same with posting it in this topic with your website link. They now have proof you actually have read the mail.