Apex domains cannot have CNAME records.
Question and response
Question
dig seppmail365.com. NS
Answer
seppmail365.com. 5 NS ns2.nodesecure.de.
seppmail365.com. 5 NS ns1.nodesecure.com.
Authority
The response has no authority records.
Additional
ns1.nodesecure.com. 5 A 192.174.68.102
ns2.nodesecure.de. 4 A 176.97.158.102
ns1.nodesecure.com. 5 AAAA 2001:67c:1bc:0:0:0:0:102
ns2.nodesecure.de. 4 AAAA 2001:67c:10b8:0:0:0:0:102
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0