smtp1.entermail.it has no CNAME records.
Question and response
Question
dig smtp1.entermail.it. NS
Answer
The response has no answer records.
Authority
entermail.it. 7625 SOA dante.enter.it. hostmaster.enter.it. 2019112801 28800 7600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0