h174.vbsmtp.com has no CNAME records.
Question and response
Question
dig h174.vbsmtp.com. NS
Answer
The response has no answer records.
Authority
vbsmtp.com. 1226 SOA will.ns.cloudflare.com. dns.cloudflare.com. 2396083841 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0