smtp.unisource.it has no MX records.
Question and response
Question
dig smtp.unisource.it. MX
Answer
The response has no answer records.
Authority
unisource.it. 86400 SOA ns1mi.infracom.it. sistemi.infracom.it. 2022071401 28800 7200 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0