mail.dnns.net has no MX records.
Question and response
Question
dig mail.dnns.net. MX
Answer
The response has no answer records.
Authority
dnns.net. 14440 SOA ns1.dnns.net. ariel.dominet.net. 2025102800 1400 7200 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0