I've listened to your presentation and your message is essentially this: you shouldn't use IP based spam filtering because that will encourage spammers to exploit flaws in the border gateway protocol, therefore you should use content filtering.
There are several problems with that thesis.
There are indeed several problems with that thesis, but that's not the one he's presented; it's a strawman.
The thesis is rather:
1. Content filters work, and no one has yet demonstrated they can be seriously subverted when correctly applied.
2. Delivery-based countermeasures do not work, and only promote an arms race that will only end when airlines chain passengers naked to their seats. Er, sorry, I mixed two up there. Whatever.
Content filtering doesn't work well.
Prove it. No, really, please do.
Everyone who has seen his legitimate mail filtered away knows this, as does everyone who receives spam despite filters being in place.
And yet not one of them is able to publish on this failure that withstands any kind of peer review? Really?
As the filtering arms race progresses it will become harder and harder to seperate spam from legitimate mail, resulting in more processing power used and more false negatives and false positives.
I don't know what reality you live in but they been attempting "progress" the filtering arms race for years now. They haven't made any progress. We're still using the same tools first inspired by Graham and others and they still adapt and filter just as well.
