ustsu1.ust.hk has no MX records.
Question and response
Question
dig ustsu1.ust.hk. MX
Answer
The response has no answer records.
Authority
ust.hk. 3600 SOA a1-251.akam.net. postmaster.ust.hk. 2020040200 3600 1200 604800 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0