It's (free) certs are not limited to websites only. It would be possible to use the certs with postix also.Let's Encrypt is a certificate authority that entered public beta on December 3, 2015[1] that provides free X.509 certificates for Transport Layer Security encryption (TLS) via an automated process designed to eliminate the current complex process of manual creation, validation, signing, installation and renewal of certificates for secure websites.
Sounds interesting to you/efa?
A couple of snippets https://dominicpratt.de/lets-encrypt-nu ... anleitung/
