Microsoft appears to be rolling out a new update to the Mail and Calendar apps with a small group of Insiders in the Skip Ahead ring that introduces Fluent Design and a brand new layout for Insiders to test and provide feedback on.
The version in question is 8700.40315, and appears to be an A/B test scenario. We too have this version of the Mail app, but we're not seeing any of the new design changes that are in testing with some Insiders. Regardless, those that do have the new design will see many changes are currently in the works.
For example, the apps now features Fluent Design effects such as reveal, and the window itself is now chromeless with the titlebar now being integrated seamlessly with the rest of the app. It also appears Microsoft is redesigning the email list UI too.
Hopefully this design will roll out to Insiders more broadly over the coming weeks. In the meantime, are you excited about these new changes? Let us know in the comments!