I have a receive connector in Exchange 2010 that will allow an anonymous relay from a device. The device will only pass the UPN name i.e. device1 and the 2010 connector will append the defaultdomain setting for both the mail from: and recpt to:
In 2013 with the exact same defaultdomain setting it will not append the the default domain that is configured. Running Exchange 2013 SP1 Cu11
Anyone else run across this ? very easy to repro