mx-pool1.myfibermail.com has no CNAME records.
Question and response
Question
dig mx-pool1.myfibermail.com. NS
Answer
The response has no answer records.
Authority
myfibermail.com. 9825 SOA ns1.epbinternet.com. poc.epbinternet.com. 2026022001 10802 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0