Apex domains cannot have CNAME records.
Question and response
Question
dig hostedemailservice.com. NS
Answer
hostedemailservice.com. 5 NS ns3.hostinguk.net.
hostedemailservice.com. 5 NS ns1.hostinguk.net.
hostedemailservice.com. 5 NS ns2.hostinguk.net.
Authority
The response has no authority records.
Additional
ns1.hostinguk.net. 5 A 84.22.166.197
ns2.hostinguk.net. 5 A 217.194.209.2
ns3.hostinguk.net. 5 A 109.169.17.171
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0