cdmondns-01.com has no MX records.
Question and response
Question
dig cdmondns-01.com. MX
Answer
The response has no answer records.
Authority
cdmondns-01.com. 3600 SOA ns1.cdmon.net. hostmaster.cdmondns-01.com. 1 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0