I don't think this is a specific Answerbank problem. I have several email addies, and the one I use for Answerbank never gets spammed, although the other one (which I use more) gets about 7 mails a day - irritating, but not excessive. There are several ways you can get onto unwanted mailing lists; have a look at this useful little article:
http://poemsplace.net/archive/fpoemsplacefrm2c915.
html
. DON'T whatever you do hit the "reply" to be unsubscribed - this only signals that they have hit a valid addy, and you will get even more. If all else fails, and it's really distressing you, scrap your email addy and get a new one.