auth2.dns.gxn.net has no MX records.
Question and response
Question
dig auth2.dns.gxn.net. MX
Answer
The response has no answer records.
Authority
dns.gxn.net. 86400 SOA auth1.dns.gxn.net. hostmaster.gxn.net. 2013060301 28800 7200 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0