Apex domains cannot have CNAME records.
Question and response
Question
dig xsend.email. NS
Answer
xsend.email. 5 NS ns-1508.awsdns-60.org.
xsend.email. 5 NS ns-812.awsdns-37.net.
xsend.email. 5 NS ns-449.awsdns-56.com.
xsend.email. 5 NS ns-1674.awsdns-17.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0