Apex domains cannot have CNAME records.
Question and response
Question
dig helpscoutemail.com. NS
Answer
helpscoutemail.com. 4 NS ns-1102.awsdns-09.org.
helpscoutemail.com. 4 NS ns-730.awsdns-27.net.
helpscoutemail.com. 4 NS ns-484.awsdns-60.com.
helpscoutemail.com. 4 NS ns-1795.awsdns-32.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0