This type of effort is usually done to harvest email accounts to spam or for other nefarious purposes. One of these types bothered to admit what s/he was doing openly to me in 2006 via yahoos instant messaging client. Offering the information to the authorities is pointless. I sometimes seriously consider this really is an oligarchy and all of the people in positions of power are hell-bent on screwing every last one of the little guys - without gel if possible.
Exceptions would be our fearless reporters at El Reg, and the honest, clean commenters such as the ones above and below me, here.