I want to upgrade my exchange serv 2010 sp3 to a dag of exchange 2013 sp1.
For now three servers are in cohabitation mode (2 exch 2013 and 1 exch2010).
Everything look fine except the communicaion between a mailbox on a 2013 database and mailboxs still on exchange 2010 database. The other way work fine.
All mails from the exchange 2013 mbx to an exchange 2010 mbx are in state waiting and never deliver.
Can you help me?