Outlook use Autodiscover when creating account, update data and such. Sometime the root domain have internet site or it is redirect to IIS with bad certificate causing outlook to pop
By updating VM to the most current configuration version on Hyper-v hosts you get the best compatibility option on the VM making the VM best performance on the virtual environment.
Sometime you can run into situation that you Arbitration mailbox got deleted, this can happen if you accidentally delete them from Active Directory or during migration for older version