On Jun 12, 2014, at 10:50 AM, John C Klensin <john-ietf@xxxxxxx> wrote: > IMO, it ought to be incumbent > on anyone proposing a different "get notification, then retrieve > mail from server" model explain why their ideas will be more > successful than that 20-odd-year-old MIME mechanism. Implementing this 20-year-old MIME mechanism would be very difficult, would have limited potential payoff, and would be pretty obviously privacy-violating. And in order for it to do any good, recipients would have to refuse large attachments. So there really isn't a viable transition path from what we have now to this, and if we had this, it would make things a lot worse in some respects, and make things better in almost no respect. This functionality is very similar to the behavior of modern MUAs that will fetch images in email messages given the URL, which is in ubiquitous use as a way of bugging mail recipients to see if they actually read the message. I disable it in my MUA. Point being, the fact that this technology hasn't taken off is no indication of a lack of demand for the technology PHB was describing.