Several times? As far as I know, most people I know have never been collateral or other kinds of blacklist damage. Do you use what might be called marginal ISPs? Some large outfits such as UUNet have long refused to care enough about spam.
The ISP in question was XO -- marginal by some standards, perhaps. But as I tried to mediate the dispute, I found XO acting much more responsibly than Road Runner, which was blocking them.
I also have to say that I fear your approach would help the larger ISPs use spam as an excuse to kill off smaller ISP's... and I question the fundamental legitimacy of blocking all of an ISP's customers before there's a fair due process to establish the ISP's culpability. "Caring enough about spam" is an awfully slippery concept on which to base a blacklist.
If you can trust outsiders to have "sufficient administrative staff to deal with the inevitable mistakes and exceptions" in a spam blocking mechanism that is not blacklist, then why can't a blacklist be run properly?
Good point. That's why I favor giving users access to their spam pool when they suspect problems, and using challenge/response in certain (carefully defined) situations. A good filtering mechanism is not nearly as black and white as a blacklist.
Any fool can set up a blacklist. That many fools have and other fools have used them does not show that blacklists are bad any more than the ease of setting up an IP network shows TCP is the spawn of the devil.
I will confess that my personal experience makes it very hard for me to be rational on the subject of blacklists, as I fear that any concession to them will only encourage the creation of destructive blacklists by "fools". In general I prefer a solution that any fool can implement, because one surely will. -- Nathaniel