mx00.smtp2.eu has no CNAME records.
Question and response
Question
dig mx00.smtp2.eu. NS
Answer
The response has no answer records.
Authority
smtp2.eu. 2396 SOA ns1.nodesecure.com. do-not-reply.iag.eu. 2025044631 28800 7200 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0