Microsoft Exchange 2010: 451 4.4.0 DNS query failedhttps://i0.wp.com/windowstechblog.nl/wp-content/uploads/2015/02/4.png?fit=478%2C233&ssl=1https://i0.wp.com/windowstechblog.nl/wp-content/uploads/2015/02/4.png?resize=150%2C117&ssl=1Martien van Dijkit's all about Microsoft