Help testing Mail v0.12

Hello Mail app users and contributors :slight_smile:

After a few months, I plan to release a new version of Mail: v0.12. This version comes with a completely rewritten front-end as we had to find a replacement for the outdated Backbone Marionette framework. The new front-end is written in Vue and has become easier to maintain and fix bugs. You can find the release PR with all linked alpha, beta and RC builds on Github:

Please let me/us know if you find any unexpected behavior, bugs or regressions :wink: