The revamped Outlook mail and Calendar has been updated in the Technical Preview of Windows 10 Mobile. The updated version of the app is available via the beta version of the unified Store in the devices installed with the Technical Preview.
The version of the app changes from 17.4119.42012.0 to 17.4125.42002.0. There are no major changes included with the update as such that are mentioned on the Store page. The app is introduced as a part of the enriched user experience that comes with Windows 10 Mobile.
The app could be downloaded only by Windows Insiders who have the latest version (build 10080) of the Technical Preview available on their Windows Phone devices.
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