ns4.123net.us has no MX records.
Question and response
Question
dig ns4.123net.us. MX
Answer
The response has no answer records.
Authority
123net.us. 3600 SOA ns2.distance.net. dns.distance.net. 2023010902 3600 600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0