ps.sgnic.sg has no MX records.
Question and response
Question
dig ps.sgnic.sg. MX
Answer
The response has no answer records.
Authority
sgnic.sg. 3600 SOA ps.sgnic.sg. postmaster.sgnic.sg. 2349569770 21600 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0