Apex domains cannot have CNAME records.
Question and response
Question
dig integral-mail.com. NS
Answer
integral-mail.com. 5 NS ns-1141.awsdns-14.org.
integral-mail.com. 5 NS ns-1984.awsdns-56.co.uk.
integral-mail.com. 5 NS ns-492.awsdns-61.com.
integral-mail.com. 5 NS ns-546.awsdns-04.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0