Apex domains cannot have CNAME records.
Question and response
Question
dig thiemail.com. NS
Answer
thiemail.com. 4 NS ns-732.awsdns-27.net.
thiemail.com. 4 NS ns-1059.awsdns-04.org.
thiemail.com. 4 NS ns-1958.awsdns-52.co.uk.
thiemail.com. 4 NS ns-212.awsdns-26.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0