smtp.comdataonline.com has no CNAME records.
Question and response
Question
dig smtp.comdataonline.com. NS
Answer
The response has no answer records.
Authority
comdataonline.com. 3577 SOA dns.itline.it. admin.dns.itline.it. 2024112801 86400 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0