> On Wed, Jul 09, 2014 at 09:45:45PM -0400, Phillip Hallam-Baker wrote: > > Umm every major email client already has STARTTLS using PKIX Authentication > > using the WebPKI roots. Go take a look at them. > The MUA-to-MTA use-case is completely different. I am not talking > about the MUA-to-MTA use-case. Quite right. And FWIW, we have long made a distinction here at protocol level. The MUA-to-MTA case is called "message submission", often abbreviated as "submit", and happens on port 587. The MTA-to-MTA case is called SMTP, and happens on port 25. Although the base protocol is the same, the extensions defined for SUBMIT and SMTP are also different. It's really confusing to use the term SMTP to refer to message submission. Ned