I am self-hosted: minimal smtp server, no TLS, only direct and basic delivery of emails. I don't even pay the DNS mob, namely I use IP literals (mailbox@[x.x.x.x] and more mailbox@[ipv6:...], see smtp RFC, yeah the email guys were smart enough not to make their protocol hard dependent on DNS neither on any crypto).

I do not trust the CA system. If I ever crypt the content of an email, it would be because a guy I saw gave me its public key in some way (QR code?) face to face. For really serious stuff, I would not use smtp anyway and with some modified-standard-cipher pre-shared key anyways.