SpamFilter.rm.cnr.it has no CNAME records.
Question and response
Question
dig SpamFilter.rm.cnr.it. NS
Answer
The response has no answer records.
Authority
rm.cnr.it. 2089 SOA nameserver.rm.cnr.it. root.nameserver.rm.cnr.it. 2026022401 43200 1800 2592000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0