After reading the article and comments, it appears that what this really represents is a need for more secure email protocols. How would one go about creating and ensuring and end-to-end secure email protocol? It could be done within a domain, but once you send or receive messages outside of your domain it's up to the intermediate and end parties to keep the message secure.

I suppose you could ensure secure communications via encrypted messages and end-clients with the key, but how could such a system be ubiquitous and practical?