smtp.msg25.com has no CNAME records.
Question and response
Question
dig smtp.msg25.com. NS
Answer
The response has no answer records.
Authority
msg25.com. 1679 SOA ivan.ns.cloudflare.com. dns.cloudflare.com. 2397066657 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0