Apex domains cannot have CNAME records.
Question and response
Question
dig mailxmgses.com. NS
Answer
mailxmgses.com. 5 NS ns-936.awsdns-53.net.
mailxmgses.com. 5 NS ns-505.awsdns-63.com.
mailxmgses.com. 5 NS ns-1667.awsdns-16.co.uk.
mailxmgses.com. 5 NS ns-1289.awsdns-33.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0