in.mx2.mailhostbox.com has no CNAME records.
Question and response
Question
dig in.mx2.mailhostbox.com. NS
Answer
The response has no answer records.
Authority
mailhostbox.com. 1786 SOA andy.ns.cloudflare.com. dns.cloudflare.com. 2398009249 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0