mx01.softdebut.com has no CNAME records.
Question and response
Question
dig mx01.softdebut.com. NS
Answer
The response has no answer records.
Authority
softdebut.com. 1409 SOA neil.softdebut.com. dns.cloudflare.com. 2397316200 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0