It's much more old school, but I've been using Migadu for a few years now. I became aware of them from a blog post by 🦜 Drew DeVault's blog (npub1qnu…tgsk) (which has apparently been taken down now?)
Here it is from the Wayback Machine: https://web.archive.org/web/20240620003715/https://drewdevault.com/2020/06/19/Mail-service-provider-recommendations.html
I also think of email like postcards. There's nothing to provide security unless you and the recipient(s) agree on some encryption scheme (e.g. PGP).