Apex domains cannot have CNAME records.
Question and response
Question
dig emailservice.cc. NS
Answer
emailservice.cc. 5 NS ns-983.awsdns-58.net.
emailservice.cc. 5 NS ns-42.awsdns-05.com.
emailservice.cc. 5 NS ns-1769.awsdns-29.co.uk.
emailservice.cc. 5 NS ns-1331.awsdns-38.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0