hdcdns02.nunsys.net has no MX records.
Question and response
Question
dig hdcdns02.nunsys.net. MX
Answer
The response has no answer records.
Authority
hdcdns02.nunsys.net. 3600 SOA ns1.nunsys.net. root.hdcdns02.nunsys.net. 2025031300 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0