monadic2

Of course I'd be willing to pay for new train tracks. I've wasted days of my life in northern virginia waiting for the track to free up. And they wonder why nobody uses the train!

Speaking from personal experience working with these reputation warehouses and with handling a good deal of incoming and outgoing email volume, they aren't any more effective than other IP-based spam heuristics and if everyone configured their DKIM correctly these warehouses would be largely obsolete. I don't see a problem with crowdsourcing heuristic data per se, but email is a much narrower field than internet traffic at large and I can see a lot of the ways that poorly configured fail2ban type software could accidentally ban a lot of valid traffic.