Limitations of Teams when mailboxes are hosted on an Exchange 2010 Server.
First thing users will see is the missing Calendar button in Teams.
Implement Exchange 2016 CU3> as a Hybrid server
Move mail Flow to the Exchange 2016 server
Best - Migrate mailboxes to Exchange 2016
Best-est - Move mailboxes to Exchange Online
See post for more information
https://eightwone.com/2020/04/30/ms-teams-pre-exchange-2016cu3/











