mx02.qboxmail.com has no CNAME records.
Question and response
Question
dig mx02.qboxmail.com. NS
Answer
The response has no answer records.
Authority
qboxmail.com. 218 SOA dns200.anycast.me. tech.ovh.net. 2026020500 86400 3600 3600000 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0