mx01.enter.it has no CNAME records.
Question and response
Question
dig mx01.enter.it. NS
Answer
The response has no answer records.
Authority
enter.it. 5203 SOA dante.enter.it. hostmaster.enter.it. 2020012302 86400 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0