"Mailvelope is a browser extension for Google Chrome and Firefox that allows secure email communication based on the #OpenPGP standard. It can be configured to work with arbitrary Webmail provider." "comes preconfigured for major providers like #Gmail, #Yahoo, #Outlook dot com and #GMX but is designed as a generic solution, that should work with any provider or website." https://github.com/toberndo/mailvelope cc @question