So.. Someone Spammed With My E-mail Address??

I received four spam emails in my junk mail today that were supposedly from my e-mail address. Of course I didn't send them. I still have the time stamps for the date sent and I suppose I can tell what time someone logged into my account by that (if that's the way it's done).

For my IT savvy friends, I'll keep these and show it to you. I'd like to know how one might trace these e-mails. It isn't the first time I've seen something like this. But I'm thinking maybe a few hardcopies might lead me somewhere.

The various e-mails said it was sent "via" "amx.com," "bernina.co.il ," and "clickz.com" (I don't know how that works or what that means) and were supposedly sent to a  the same other email addresses (repeated e-mails included in the sent to), but still has my e-mail address under "sent from."

If anyone knows how this works let me know. It should be a learning experience, in the least.