If I can remember correctly, I think I've got about 4 email addresses. The reason being that I'd be too lazy to record the details of the email and so would either forget the password (which could be easily changed, I know) or actually have forgotten the email address itself.
At this present moment I have two email addresses that I use on a regular basis. I used to have three, the third being my school address for my laptop but ever since I handed it back in, I don't really use it that much. The ones I do make use of however, are dedicated toward my online accounts; Facebook, Tumblr etc, whereas my other I utilize for school and work.
I find emailing to be a great tool to get in contact with my teachers if I'm having trouble or simply want to clarify something or ask a question. I do find Facebook much easier to use to contact friends on though, considering nearly everyone I know uses their Facebook more regularly than their email.