I figured it out: The reason I'm addicted to email is that my brain expects the rules of normal conversation to apply. They don't. Unlike a face to face conversation, I don't necessarily get a response quickly. All the while, my brain is pinging my consciousness to find out what the response is so I can reply to that, or act on the new information. Multiply this by the number of email threads I'm keeping up with on a day to day basis at work and at home, and you'll see why I never feel settled or content. There's always hope that if I check my mail, I'll get that final response on the final thread, and all will be well. Even if I am up to date, it's hard to know this for certain, so the sense of incompleteness lingers in my psyche.
I think a study of people who are addicted to email and chatting should look into how those people normally communicate. Are the folks who can chat for hours with old friends the worst when it comes to this? Maybe I just need to learn to be complete with incompleteness in my life.
So, what do you think of that? I'm waiting for your reply :)