in the same scenario described here: https://docs.microsoft.com/en-us/answers/questions/208204/migrated-from-msdn-exchange-devexchange-2019-does.html
i have another error,
sometimes one user have a windows error when i try to press the "send" button of a foreward mail that he is writing,
the error is the same described here found in E365 users in August 2019:
we can confirm the bug is still present with outlook 2016 in online mode with RDP server, and Exchange 2019?