Tracking an IP address to a deleted account?

I keep getting emails from my ex boyfriend that are just mean but non threatening. Here's what he does...he makes up several fake email addresses and then sends it out from didtheyreadit.com's website. He also is using either his neighbor's wireless internet connection or possibly another wireless connection from a local business in the neighborhood. (How do I know this, because that's how he gained access to the internet when we dated.) IHe says I can't prove anything because the emails are not being sent from his internet provider so there's no way to trace them back to him. The only information I can get from the ip address is that it is out of state. I've contacted didtheyreadit.com a few times but they have not responded to me. Any help would be great.