hdccpa06.nunsys.net has no MX records.
Question and response
Question
dig hdccpa06.nunsys.net. MX
Answer
The response has no answer records.
Authority
hdccpa06.nunsys.net. 3600 SOA ns1.nunsys.net. root.hdccpa06.nunsys.net. 2026021900 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0