sdns.lbl.gov has no MX records.
Question and response
Question
dig sdns.lbl.gov. MX
Answer
The response has no answer records.
Authority
lbl.gov. 300 SOA nsx.lbl.gov. hostmaster.nsx.lbl.gov. 2022514000 14400 1800 2419200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0