Apex domains cannot have CNAME records.
Question and response
Question
dig imimailer.com. NS
Answer
imimailer.com. 5 NS ns-2027.awsdns-61.co.uk.
imimailer.com. 5 NS ns-1227.awsdns-25.org.
imimailer.com. 5 NS ns-232.awsdns-29.com.
imimailer.com. 5 NS ns-613.awsdns-12.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0