mailhost.delong.sj.ca.us has no MX records.
Question and response
Question
dig mailhost.delong.sj.ca.us. MX
Answer
The response has no answer records.
Authority
delong.sj.ca.us. 86400 SOA ns.delong.sj.ca.us. postmaster.delong.sj.ca.us. 2025053966 43200 300 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0