EFF has released STARTTLS Everywhere: free tools to encrypt email between mail servers / Boing Boing
▻https://boingboing.net/2018/06/26/hop-to-hop.html
the Electronic Frontier Foundation — as part of its ongoing quest to encrypt the whole internet (see also: Certbot, Let’s Encrypt, HTTPS Everywhere, and related toold) — has just released STARTTLS Everywhere, an automated tool that generates the certificates, helps install and configure them, and double-checks the configuration to make sure everything is safe and secure.
Unless you run your own mail server, you can’t do anything with this: but you can (and should) send it along to whomever administers your email and get them to have a look. It’s totally free, and solves a real problem, widely observed in the wild, of mass email surveillance.