ns.delong.com has no MX records.
Question and response
Question
dig ns.delong.com. MX
Answer
The response has no answer records.
Authority
delong.com. 60 SOA ns.delong.sj.ca.us. postmaster.delong.sj.ca.us. 2026011634 43200 300 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0