Microsoft Teams works best when your mailbox is in Exchange Online, and you have a license for SharePoint Online, and you have OneDrive for Business enabled.
When you have your mailbox in Exchange on-premises your options are limited, you have basic Teams functionality like audio/video and files, but that’s basically it. Not a trace of the calendar or the option to manage meetings in Teams. This is what ‘cloud partners’ have been telling me for a long time: “no, you must migrate your mailbox to Exchange Online” (and we can help you with that I was they were thinking…)
But, if you have Exchange 2016 CU3 or higher things get better (I’m sorry if you are still running Exchange 2010). To enable the integration of Teams with on-premises Exchange 2016 you need to configure OAuth in your on-premises environment as outlined in my previous blog, and assuming you have Exchange hybrid configured of course.
When you have OAuth configured, Teams can access the on-premises mailbox on behalf of the user that’s logged on in Teams, making it possible to retrieve the user’s calendar. After configuring OAuth and without any additional configuration in Teams the user’s on-premises calendar (here in Exchange 2019) automagically appears:
In the Teams client this is a view of your calendar, and using the new meeting option you can create new Teams meetings, invite people, set recurrence, select a channel etc. Invites are sent to other recipients using the regular Exchange process, and when accepted a response is sent (or not) back to your inbox. I never knew this was possible, but this is cool stuff.
Integrating the calendar into Teams is a nice addition and it can help users with their daily productivity task. From a compliance perspective things are a bit different. Chats for example are not stored in the user’s mailbox, this is only possible for mailboxes in Exchange Online. The process responsible for copying Teams chat data from the Azure storage (outside of Office 365) simply cannot access the folder in the user’s mailbox.
But, for on-premises calendar integration in your Teams environment this is very nice.
How Exchange and Microsoft Teams interact – https://docs.microsoft.com/en-us/microsoftteams/exchange-teams-interact
Configure OAuth authentication between Exchange and Exchange Online organizations – https://docs.microsoft.com/en-us/exchange/configure-oauth-authentication-between-exchange-and-exchange-online-organizations-exchange-2013-help