ns3.cdmon.net has no MX records.
Question and response
Question
dig ns3.cdmon.net. MX
Answer
The response has no answer records.
Authority
cdmon.net. 3600 SOA ns1.cdmon.net. hostmaster.cdmon.net. 2023091406 10800 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0