User %1 with mailbox %2 can't synchronize their mobile phone with their mailbox because the mailbox is on an Exchange 2010 ...

User [%1] with mailbox [%2] can't synchronize their mobile phone with their mailbox because the mailbox is on an Exchange 2010 Mailbox server or a later version. Exchange ActiveSync blocks synchronization for users who have mailboxes hosted on Exchange 2010 servers or later versions. If you want users who have mailboxes on Exchange 2010 servers or later versions to use Exchange ActiveSync, you can modify the web.config file for the Microsoft-Server-ActiveSync virtual directory in Internet Information Services Manager by setting the value of BlockNewMailboxes to false.