Then, if it ends up not being you, I guess you are scott free while this user (which the ISP I just called confirmed it does indeed belond to their netrange) is going to get reamed.

Oddly enough, the company is actually based in Canada, and oddly enough, they have verified it's from the same user switching over after an IP renewal (usually automagic). They have, as I predicted, asked I send the origonal emails where it shows your IP address with unmodified headers to their abuse admin (with whom I spoke with over the phone) and will begin an investigation.

Canadian company and ISP.. and only from the same ISP as the one person who threatened to send me spam in the first place.... nah.. couldn't be you.