Thus said Michael Richardson on Thu, 05 Jun 2025 15:55:38 -0400: > > Do we support client certificate submission during TLS > > negotation? No. If this is what you want ... well, I'm a little > > surprised, as I work in an environment that makes heavy use of > > TLS client certificates and as far as I know this is never done > > for SMTP (web servers, yes, but SMTP, no). I would have to look > > at what it > > Yes, it never took off, but I've been using this for 25+ years.
Nice to find a fellow traveller who still knows what SMTPS on port 465 is and actually still uses it. I still maintain a SMTPS submission server on port 465, however, it's rarely used anymore. For Ken and those who may not have used it much, it's a fine way to allow authenticated and authorized relaying as you get strong encryption to protect the channel and you get authentication and authorization because the peer certificate is verified against your own CA. Andy
