Apex domains cannot have CNAME records.
Question and response
Question
dig enflow.email. NS
Answer
enflow.email. 5 NS ns3.enflow.nl.
enflow.email. 5 NS ns1.enflow.nl.
enflow.email. 5 NS ns2.enflow.nl.
Authority
The response has no authority records.
Additional
ns1.enflow.nl. 5 A 185.233.173.153
ns2.enflow.nl. 5 A 185.233.173.150
ns1.enflow.nl. 5 AAAA 2a0c:eb00:0:f10:185:233:173:153
ns2.enflow.nl. 5 AAAA 2a0c:eb00:0:f10:185:233:173:150
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0