mailhub.eon.com has no CNAME records.
Question and response
Question
dig mailhub.eon.com. NS
Answer
The response has no answer records.
Authority
eon.com. 3600 SOA ns0009.secondary.cloudflare.com. hostmaster.adacor.net. 2026022512 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0