Back in the days of dial-up modems and transfer speeds measured in hundreds of bits per second, unwanted email messages were actually felt as a significant dent in our personal pocketbooks. As increases in transfer speeds outpaced increases in spam traffic, the hundreds of unwanted emails we received per week became more of a nuisance than a serious financial threat. Today sophisticated spam filters offered by all major email providers keep us from seeing hundreds of unwanted emails on a daily basis, and relatively infrequently allow unwanted messages to reach our coveted Inboxes.

I'd have to think about this a bit but at least he proposes a migration path.

Hypertext Mail Protocol (a.k.a. Stub Email): A Proposal