Spam will not
stop until the last spammer is dead.
Actually, it's really simple to stop spam. Simple, not easy.
You just need to delegate responsibility along with authority when
handing out netblocks, registering domain names, and the like.
When there were only tens of thousands of mail nodes (few of which had more than a
few thousand accounts it was practical to put the responsibility on postmasters.
With tens of millions (often with millions of customers) that is no longer so.