By default, a Receive connector named “Default Frontend <ServerName>” is created when Exchange is installed. This Receive connector accepts anonymous SMTP connections from external servers. If you want to restrict inbound connections from external servers, modify theDefault Frontend <Mailbox server>...
Please download and installWindows Server 2008 R2 Service Pack 1 (KB976932). https://www.microsoft.com/en-us/download/details.aspx?id=5842