From the article: “Both Google and Yahoo are working on an implementation of the open source standard OpenPGP that works entirely within the browser. The two projects are a work in progress, so some details might change, but the idea is to create a browser extension that will deal with all the pains of using PGP, making it as easy as possible to use, and allowing users to send emails that nobody—including Google and Yahoo—can read, other than the sender and the recipient….Google and Yahoo are not the only ones trying to make more secure email easy. There’s Mailvelope, which offers a browser extension similar to the one Google and Yahoo want to do.”
Read the full Motherboard article here: https://motherboard.vice.com/en_us/article/google-yahoo-end-to-end-email-encryption-work-in-progress