@a @mwl @dalias Dang, I do use Linode.
On the bright side, yes, I have a Let’s Encrypt CA and DNSSEC/DANE, MTA-STS, CAA, and all the acronyms. I also edited the Postfix config files to require TLS for outbound connections to some servers that I know will never not support it, like Google, Microsoft, and a few others.