mailproxy7.ent.usda.gov has no MX records.
Question and response
Question
dig mailproxy7.ent.usda.gov. MX
Answer
The response has no answer records.
Authority
ent.usda.gov. 15 SOA ns1.usda.gov. duty\.officer.usda.gov. 1750 90000 9000 90000 15
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0