zmx.osinet.sg has no MX records.
Question and response
Question
dig zmx.osinet.sg. MX
Answer
The response has no answer records.
Authority
osinet.sg. 300 SOA dns1.pacificinternet.com. noc.pacificinternet.com. 2025121602 7200 1800 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0