> On Feb 4, 2016, at 11:22 AM, John C Klensin <john-ietf@xxxxxxx> wrote: > >> I am quite comfortable at this time with a requirement of >> better than SSLv3 for SMTP on the public Internet. > > Unless there is a fallback to clear text, I am not. Yes, of course with cleartext transmission in the absence of STARTTLS support. I had expected that would have been clear from context. The point being that systems that are STARTTLS-capable are at this point essentially without exception capable of TLSv1 or better. My statement should have said "requirement of better than SSLv3 to complete a STARTTLS handshake". I am not suggesting that we've reached sufficiently broad STARTTLS adoption to make it realistic to end support for cleartext SMTP. At https://www.google.com/transparencyreport/saferemail/ we see a very small positive slope in the percentage of TLS outbound mail (~2% per year) and no sign of growth in TLS inbound mail (I'm guessing the bulk email senders don't much care for TLS and send more traffic on weekdays than weekends). -- Viktor.