Some customers choose an Exchange Hybrid configuration for Teams for various reasons such as strict compliance requirements.
I haven't found any documentation stating the Teams related services affected when using Exchange Hybrid instead of EXO.
This is a list I came up with and would appreciate any comment/input
Meetings: cannot be scheduled in Outlook desktop, only in the Teams client, or Outlook web EDIT: the add-in is supported in Exchange Hybrid- Voicemail: not available in Teams client, only in Outlook link
- "Share to Outlook" a message in Teams requires EXO.
- Chats: are no longer saved/displayed in Outlook with OnPrem Mailbox - they can be searched via eDiscovery and exported Search for Teams chat data for on-premises users
- SharePoint Online: unclear if alerts notifications, comments/likes on page still work with Hybrid or require EXO
- Planner: limitation on commenting and receiving notifications, but unclear what "may" means
- If your organization is not using Exchange Online for your account, you may not be able to comment on tasks in Planner. link
- Planner has full functionality when your user has a product license that includes Exchange Online. Planner users without Exchange Online may have issues with viewing or adding comments to a task. link
- email will only be sent to users who have a product license that includes Exchange Online. Users at organizations using on-premises Exchange Server or hybrid configurations may not receive all Planner emails. link
- To Do: Works only with Exchange Online link
- Bookings for Teams only works with Exchange Online (FAQ).
- Require mailboxes to be in EXO - you can still run EX hybrid but the user using Bookings must have an online mailbox - link
- If you're using an Exchange hybrid configuration, we recommend that you thoroughly test mail flow between on-premises Exchange and Exchange Online when changing the default domain.
