rs7402.luxsci.com has no MX records.
Question and response
Question
dig rs7402.luxsci.com. MX
Answer
The response has no answer records.
Authority
luxsci.com. 300 SOA dns1.easydns.com. zone.easydns.com. 1771813406 43200 10800 1857600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0