smtp.netflowservices.com has no CNAME records.
Question and response
Question
dig smtp.netflowservices.com. NS
Answer
The response has no answer records.
Authority
netflowservices.com. 68 SOA x.ns.joker.com. hostmaster.joker.com. 2024092653 14400 3600 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0