There are several possibilities here.
Maybe he doesn't want to see you. There's a difference between missing someone and wanting to see her. Maybe he knows it wouldn't work out (again), but he was reminiscing about your past relationship and wanted to thank you for your kindness. After you break up with someone and time passes, your view of things becomes more objective. He might have realized how good you were to him and felt the need to tell you. That still doesn't mean he wants to try a relationship again.
On the other hand, maybe he does want to try dating again. Maybe his e-mail was testing the waters. He's thinking about trying to get back together, but he doesn't know how you will respond, so he's being slow and cautious. He might even be waiting for you to make the next move.
Maybe he wants to be friends. After being apart and gaining some objectivity, he realizes that dating again wouldn't work, but that you are special to him and he wants you in his life.
I suggest you think very carefully before dating him again or even being friends. You broke up for a reason. You still haven't gotten over him, clearly. I wouldn't attempt another relationship without being sure. It could work out, but I would hate to see you get hurt if it doesn't.
Thanks for the question.