Microsoft has acknowledged a known issue with Windows Server 2016 and Exchange Server 2016, and has advised not to deploy this configuration for now.
In Exchange Server the Get-MailboxDatabaseCopyStatus cmdlet may return the wrong activation preference value for a database copy.
When moving an Exchange 2013 mailbox to a database that is excluded from provisioning you receive an error.
A critical issue has been reported with the behavior of litigation hold in Exchange Server 2013 and Office 365.
New bugs have appeared in Exchange Server 2013 Cumulative Update 6 impacting Hybrid customers.