mailout.thzhost.com has no CNAME records.
Question and response
Question
dig mailout.thzhost.com. NS
Answer
The response has no answer records.
Authority
thzhost.com. 591 SOA dns1.thzhost.com. dnsadmin.thzhost.com. 2026022602 3600 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0