mx01.sparkmail.it has no CNAME records.
Question and response
Question
dig mx01.sparkmail.it. NS
Answer
The response has no answer records.
Authority
sparkmail.it. 550 SOA edward.ns.cloudflare.com. dns.cloudflare.com. 2393074953 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0