A new Windows 10 Mobile build was released to those in the fast ring of the Insider program. MIcrosoft didn't include a changelog but it's labeled as a configuration update so those in the Fast Ring should apply it.
The Outlook Groups app has been released for Windows Mobile. The app from Microsoft allows interaction with work groups including messaging and scheduling, all in one place. Groups can collaborate with Office documents and OneNote notes.
Outlook Groups is also available on Android and iOS.