[frik]

It would be great to have a new modern open source email app on iOS, Android and desktop OS. I want a GMail app clone (conversation view), but open source (= doesn't phone home to the creator) that works with IMAP.

Vivaldi browser (unofficial Opera successor) is working on an HTML5 powered email app, though will it be open source?

On Android there is open source K9Mail app but it's pretty old fashion, no conversation view.

I envision a new lean Mozilla browser (like Firefox was to Mozilla Suite back then) based on Rust powered Servo-HTML-engine and a HTML based UI. Additionally an email app addon would fit in my vision.