mx.seo.it has no CNAME records.
Question and response
Question
dig mx.seo.it. NS
Answer
The response has no answer records.
Authority
seo.it. 601 SOA ns20.tuonomeregistrar.net. tech.tuonomeregistrar.net. 2025022701 86400 7200 2592000 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0