ns4.ja.net has no MX records.
Question and response
Question
dig ns4.ja.net. MX
Answer
The response has no answer records.
Authority
ja.net. 3600 SOA ns0.ja.net. operations.ja.net. 2026022000 28800 3600 3600000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0