451 4.4.0 DNS query failed Exchange 2010https://i2.wp.com/windowstechblog.nl/wp-content/uploads/2015/02/error.png?fit=924%2C63&ssl=1https://i2.wp.com/windowstechblog.nl/wp-content/uploads/2015/02/error.png?resize=150%2C32&ssl=1Martien van Dijkit's all about Microsoft