hdccpa07.nunsys.net has no MX records.
Question and response
Question
dig hdccpa07.nunsys.net. MX
Answer
The response has no answer records.
Authority
hdccpa07.nunsys.net. 86400 SOA ns1.nunsys.net. root.hdccpa07.nunsys.net. 2026020300 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0