ns.otherdns.com has no MX records.
Question and response
Question
dig ns.otherdns.com. MX
Answer
The response has no answer records.
Authority
otherdns.com. 1800 SOA dns1.afrihost.com. support.afrihost.com. 2006082100 28800 180 2419200 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0