mailgate.oit.one has no CNAME records.
Question and response
Question
dig mailgate.oit.one. NS
Answer
The response has no answer records.
Authority
oit.one. 1712 SOA carmelo.ns.cloudflare.com. dns.cloudflare.com. 2397343764 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0