There is Currently No Route to the Mailbox Database
KB ID 0001413 Problem Background: Just introduced Exchange 2016 into Exchange 2013 Environment. Mailboxes on Exchange 2016, can send external mail and internal (to Exchange 2013) mail. No mail flows from Exchange 2013 to Exchange 2016. External mail to Exchange 2016, (which flows thought the 2013 server,) also fails. Event ID 5006 Cannot find information about owning Mailbox Server {server-path} for database {database-path} in routing...