1 year...and he's back?!!?!?!

[Logos]

I hate to say it, but I'm dumb enough that I kind of like being in touch in some way with everyone who's paraded through my life, and I'm centered enough that it doesn't particularly f--- me up. So, thought the guy sounds like a dick and doesn't deserve whatever emotional satisfaction he might get from talking to you again, do whatever you feel comfortable with. If you're just going to obsess just because they guy has exchanged a few emails with you, then screw it, but if it would amuse and not upset you to hear more about his shitty life now, then answer him. Just don't be too nice.

[casco]

There are 2 reasons why he would do it - either he wants an ego boost and a challenge to see if he can get you to try and win him back, or he genuinly misses you. He is obviously thinking about you, and if he thought you were a witch he wouldn't want to get back in touch, so there must be something there.
I've had it happen to me a few times, and its usually from girls who realise that the grass isnt greener on the other side, or that they made a mistake breaking up with you - usually when they have met someone else who is 10x more annoying than you ever were.

Its usually a sign of neediness on their part, if you really miss them, then why not get back in touch? If they were a prat, totally ignoring them is far more effective