Exchange 2010: 451 4.4.0 DNS query failedhttps://i2.wp.com/windowstechblog.nl/wp-content/uploads/2015/02/3.png?fit=443%2C516&ssl=1https://i2.wp.com/windowstechblog.nl/wp-content/uploads/2015/02/3.png?resize=150%2C150&ssl=1Martien van Dijkit's all about Microsoft