It's fortunate that none of those are "checked" in the ASCII art, because none of them actually apply. > Requires immediate total cooperation from everybody at

It's fortunate that none of those are "checked" in the ASCII art, because none of them actually apply. > Requires immediate total cooperation from everybody at once False. As a silver lining to the Google/Microsoft email oligopoly, those providers could announce that anyone wanting to send email to those services will have to implement this protocol, and it could be done in less than a year. > Unpopularity of weird new taxes Irrelevant. No taxes involved - there's no money here, and users won't care if their mail takes an extra few seconds to send, because they don't expect email to be low latency anyway > Public reluctance to accept weird new forms of money Irrelevant - no new money involved. > Huge existing software investment in SMTP Irrelevant - a small number of server software are used by the majority of users. Also, see earlier point about oligopoly. > Sending email should be free Bad idea, and irrelevant, because it still would be. I suggest you put thought into copypasta before putting it into a comment.