Received email from mailer daemon?

I received an email from a no-replylayi@mailer-daemon.com,concernin… about an unpaid bill. I am concerned about opening up the zip file that came with it cause I don't have a card with that big of credit line, and they only refer to me as "dear client".but at the same time I want to check it out cause I was one of the many people that was effected by the Sony Playstation Hacking. Can anyone please give me some advice on what my next step should be