It's not that spam isn't an important problem, nor that it's entirely out of scope for IETF. But the lack of agreement on the nature of the problem, along with the level of naivete in these discussions, suggest that it will be a long time before these discussions can hope to bear useful fruit. And this isn't a particularly effective venue to work on that problem. If nothing else, the NSRG antispam research group has been talking about this for several months, and there's no point in repeating the same arguments on the IETF list that they've been having over there. see https://www1.ietf.org/mailman/listinfo/asrg