Following random links on KJ's blog and then other links on those sites I found this one.
Attention shifts to spam containment

Near the middle is this is line, 'Mitchell said ISPs are businesses and "have to look at the bottom line and their profitability."' That just pisses me off because attitudes like that are never going to make any real difference when fighting people who are also just looking out for themselves and THEIR profits. Yes they do have to worry about their profits but stopping bulk emails being sent might be worth more to them if users like myself don't have to guard our email address like it's an authorisation code for a nuclear missle.

Good on anyone who takes up this apparently 'new' idea.