custmx.cscdns.net has no MX records.
Question and response
Question
dig custmx.cscdns.net. MX
Answer
The response has no answer records.
Authority
cscdns.net. 14400 SOA udns1.cscdns.net. hostmaster.cscdns.net. 2007080916 28800 7200 604800 14400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0