Tuta Mail is an open-source end-to-end encrypted email service with ten million users. Its creator, Tuta, is based in Germany, where it's involved in developing post-quantum secure cloud storage and file-sharing solutions for the government.
https://tuta.com/blog/pqdrive-project
Today, Tuta announced the launch of TutaCrypt, a new protocol designed to protect currently exchanged communications from 'harvest now, decrypt later' attacks.
"With TutaCrypt we are revolutionizing the security of emails. For the first time, people can now send and receive emails that are encrypted so strongly that not even quantum computers will be able to break the encryption and decipher the messages," stated Tuta's CEO, Arne Möhle
New Tuta Mail accounts will get TutaCrypt upon creation, and existing users will get the superior protocol through a gradual key rotation that will take place over the next period.
@ecksmc Tutanota user for years now. Very happy.