Office 365, Unified Groups
The best part of Unified Groups is that they can function like a shared mailbox and calendar in Office 365 email and that any individual can create these Unified Groups as they need.
Unified Groups are groups based exclusively in Office 365. Anyone in Office 365 can create these groups when they add individuals as a collaborator in a Microsoft Team or on a plan in Planner, or by creating a new group in Outlook on the Web.
To learn more about how to create and use Unified Groups, please refer to the Microsoft Office 365 Groups document: