S/MIME has recently become available for G Suite for education. This offers digital signage of emails and enhanced encryption where supported by the recipient. There are a few steps to setting this up. Enable on the Admin Console for users Generate pfx certificates for users (or get them to do it) Upload pfx into GMail settings - either the user does this or you can do it with GAM GAM command: gam user jim@acme.com add smime file jim.pfx password p@ssw3rd default The password is for the certificate - not the user's password. Optionally force the use of S/MIME via a content compliance rule for certain recipients. Useful links: GM Commands Commodo - one source of certificates How to make a pfx