Secure email has been around for a while, for example, gpg tools have been around for macOS since quite some time. A recent podcast episode of the Mac Power User podcast tipped me to look at certificates, the relatively easy setup process within apple mail. It was only a quick search from there that I discovered that my employer, the University of Tübingen provides such certificates, issues such certificates.
The University of Tübingen provides secure email using S/MIME based certificates within the framework of the "public key infrastructure" of the german research net (DFN)
Die Universität Tübingen unterstützt das S/MIME-Verfahren im Rahmen der Public-Key-Infrastruktur (PKI) des Deutschen Forschungsnetzs (DFN).
The most effort requires to walk by the user help desk, which is actually a wonderful distraction given the current spring weather!
Update Friday; March 17, 2017: Nice overview comparing S/MIME and OpenPGP: