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The current environment is a hybrid deployment of Exchange 2019. The Teams calendar of local email users can be accessed, and the meeting information created by Teams can also be synchronized to the calendar of the local Outlook client.
The problem we are facing now is: creating a new meeting in the Teams calendar and then opening the scheduling assistant, our own and other attendees' free and busy status is unknown.
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Hi,@Kun Bao
Thanks for posting your question in the Microsoft Q&A forum.
Given the complexity of your current environment, I need to confirm a few pieces of information:
1.Have all of your organization's users migrated to Online? If not， can you describe the state of your current user?
2.Can you see a user's busy/idle status in Outlook?
3.Is the user with the problem receiving an “Unable to update” error in Outlook?
Your response is very important for us to solve your problem, thank you for your support and understanding.
1、Most of users are on-prem mailbox users
2、I can see free/busy status in Outlook
3、 No error appear in Outlook
1、Most of users are on-prem mailbox users
2、I can see free/busy status in Outlook
3、 No error appear in Outlook
Through testconnectivity.microsoft.com， I run the Teams Calendar Tab Test. The test is passed, but there is some error shown in the log.
Hi，@Kun Bao
It's nice to hear back from you.
If you are working in Teams calendar directly and you try to invite other on-prem users to a Teams meeting, your users/identities need to be synced with Azure AD Connect to be visible in Teams. While you can type the full email address from an on-prem user to invite them, if this mail domain is an accepted domain in O365 and there is no recipient in O365, mail delivery will fail with unknown recipient as the lookup will be done in O365 Global Address Book. Mailbox itself doesn’t need to be moved to EXO, but the identity should be synced.
For details, please refer to this link:https://techcommunity.microsoft.com/blog/exchange/configuring-teams-calendar-access-for-exchange-on-premises-mailboxes/1484009
If my answer is helpful to you, please mark it as the answer so that other users can refer to it. Thank you for your support and understanding.