Secure Correspondence
GPG public key
Public GPG key
List of GPG mail solutions:
macOS https://gpgtools.tenderapp.com/kb/how-to/first-steps-where-do-i-start-where-do-i-begin-setup-gpgtools-create-a-new-key-your-first-encrypted-mail Linuxhttps://ssd.eff.org/en/module/how-use-pgp-linux
Windows https://ssd.eff.org/en/module/how-use-pgp-windows-pc
iOS https://itunes.apple.com/app/ipgmail/id430780873?mt=8
Android https://play.google.com/store/apps/details?id=org.sufficientlysecure.keychain