undefined.sevstar.net has no MX records.
Question and response
Question
dig undefined.sevstar.net. MX
Answer
The response has no answer records.
Authority
sevstar.net. 7200 SOA ns.sevstar.net. admin.sevstar.net. 1771595700 3600 7200 604800 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0