Microsoft has started rolling out a new Groups features in its Outlook.com webmail, which should be familiar for those of you already using Office 365 groups. By adding contacts to a group, you’ll be able to send them messages, share files, schedule events on a group calendar, and more, and it's worth noting that you can add group members using other emails services than Outlook.com
This new feature is available in the left panel of the Outlook.com web app. If you’be been invited to different mutiple Outlook.com Groups, there’s also a “Follow in inbox” option which will send all group conversations and calendar events in both the group mailbox and your personal Outlook.com inbox.
We are rolling this out worldwide on Outlook.com and expect all users to have access by the end of August 2019 with expanded support to create a group in mobile in Fall of 2019, the company said yesterday in the blog post announcing the new feature. You can learn more about how to get started with Outlook.com Groups on this support page.