clock.isc.org has no MX records.
Question and response
Question
dig clockisc.nwtime.org. MX
Answer
The response has no answer records.
Authority
nwtime.org. 3600 SOA ns1.everett.org. postmaster.nwtime.org. 2026012500 3600 14400 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0