It's FOSS - https://itsfoss.com/tutanota-review/
A little while back, I reviewed an email service call ProtonMail. I had been a long time ProtonMail user by that time, and I had little negatives to say about the service. In fact, I went so far as to say that everyone should use it.
Since then, I have heard of another email provider that you may be interested in. It’s a little different, but it touts some of the same features ProtonMail does: privacy, security, open-source code, etc. It’s called Tutanota, and like ProtonMail, I am a very big fan.
Without wasting any time, here’s why I think