I've read the announcement[1] and I don't see how this deprecation has anything to do with SMTP. Is it because the sending MTA will present its own server certificate as a client certificate to the receiving MTA? I thought most of this traffic was outright unencrypted or opportunistically encrypted with self-signed certs.
Do most SMTP server require, or even use, certs issued by a CA?
Do most SMTP server require, or even use, certs issued by a CA?
[1]: https://letsencrypt.org/2025/05/14/ending-tls-client-authent...