mail10.sendnode.com has no CNAME records.
Question and response
Question
dig mail10.sendnode.com. NS
Answer
The response has no answer records.
Authority
sendnode.com. 216 SOA a.ns14.net. domainadmin.w3work.de. 2025120912 43200 7200 1209600 360
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0