I have a T1 line - this is not your average ISP issue. And, it's not really a scumbag ISP - they are not, from what I know, an especially spammer-friendly ISP - they just got on someone's nerves one day.

Look, I am a systems administrator, and I deal with a lot of spam every day, for myself as well as people who have email on my servers. I don't get what the problem is with using a labeling approach to spam, instead of simply blocking it. Yeah, it takes processing power, and time to administer, but it's way better than spending my time (and $) chasing after my ISP or filing lawsuits, or dealing with clients who can't send mail to one person or another, or what have you to stop this.

I think that ultimately, the blacklisting approach is 1) a losing battle - (how long will it take for most addresses to be blocked?) and 2) just manages to make the lives of more and more legitimate people difficult. For every block of a class C address (or several, in my case), you might be blocking one spammer, but 10s or perhaps even 100s of legit people who just want to send email. And the stories I've heard about nonprofit organizations that send a mass-email to their constituencies, and one irate person who may have been on the list accidentally complains, somehow they get on spews, or some such list, and all of a sudden, they have real trouble communicating with people. This whole approach is just, IMHO using a bear trap for a mouse.