Guys: How much emailing is too much?

We worked together for about a month, and he definitely gave a lot of signals that he liked me. Then our project ended, we stopped working together. He emailed me out of the blue in December, so I emailed back (he was out of town, I wished him a Merry Christmas, that's basically it), no reply. In early January I emailed to see if he was back in town yet (very very short, only asked how his holidays were and if he was back), no reply. I decided that I would only email him once more to make sure he knows that I am interested in him (as I had never actually told him). Sent him a nice email that I missed seeing him about 3 weeks after the last one and that he should call me. No reply yet. I'm done trying to initiate communication, there will be no more emails unless I hear something back, and even then I'm pretty wary of someone that would string me along like that. I'm just wondering if I overdid it with the emails? What is the limit, and does it depend on the nature of the emails?