I worked for Match.com. I can help with your complaint. First, call their customer service, they can run a test on the emails. Every so often there is a tech issue either on Match.coms end or the customers end. The tech department can work with you, although it will take a few days before they can contact you regarding your tech issue.
As for the "Mysterious" emails, there is no such thing. Your account has a record of emails sent and recieved, as well as the other members. A rep can not go into another members account without their permission and tell you if that person has read your email. I took calls such as yours only to find out that the other party recieved the email and simply didn't respond. It could be they began dating someone, went out of town, etc. There are however fraudulant profiles which Match.com shuts down immeditaely. If I were single I would use their service, but I would be very careful as I am on Myspace.