> No on expects a mailserver cert to be from an authority, you can self sign and it works fine. Yes, but that's A Bad Thing(TM) -- it means that MITM'ing a mai

> No on expects a mailserver cert to be from an authority, you can self sign and it works fine. Yes, but that's A Bad Thing(TM) -- it means that MITM'ing a mail server also "works fine"! Now, personally, I'm not a big fan of DNSSEC (especially considering how widespread 512- and 1024-bit keys were!) but I was hopeful that "DNS-based Authentication of Named Entities" (DANE) [0] would become widely supported once it was fully standardized. Unfortunately, that didn't happen -- especially in the browsers! After the explosion in growth of "HTTPS everywhere", transport security for e-mail was the next big (unencrypted) problem that needed to be addressed in my opinion. Luckily, both Exim and Postfix (my MTA of choice) gained support for DANE so while progress was technically made, widespread adoption never really happened there either (mostly due to the dependency on DNSSEC, AFAICT). In the meantime, though, "SMTP MTA Strict Transport Security (MTA-STS)" appeared on the scene and has since been formalized as RFC8461 [1]. In many ways, it's technically superior to DANE and, importantly, does not rely on DNSSEC. It does have the same reliance on the "WebPKI" as the browsers so it's certainly not perfect; it's still a huge improvement, though, and it's certainly better than opportunistic encryption which is trivial to MITM. Anyways, as MTA-STS was designed by folks at Google, Microsoft, Comcast, and Oath, I'm hopeful, once again, that we'll eventually get to the point where (at least) the overwhelming majority of e-mail is encrypted in transit as it passes from MTA to MTA on its way to the recipient's mailbox. One of the few good things about so much of the e-mail nowadays being handled by Google and Microsoft is the huge volume of mail that will suddenly just start being encrypted in transit, overnight, when just those two enable MTA-STS in their mail infrastructure. I haven't kept up with progress on MTA-STS since leaving my previous job (which included responsibility for the mail infrastructure) about two years ago -- shortly after it became a standard -- but I'd love to find out that it's already been widely rolled out by the big players in the meantime! I suppose it's about time to catch up on the last two year's worth of messages sitting unread in the "mailops" folder in my mailbox! -- [0]: https://en.wikipedia.org/wiki/DNS-based_Authentication_of_Named_Entities https://en.wikipedia.org/wiki/DNS-based_Authentication_of_Na... [1]: https://tools.ietf.org/html/rfc8461 https://tools.ietf.org/html/rfc8461