smtp11.moh.gov.sg has no MX records.
Question and response
Question
dig smtp11.moh.gov.sg. MX
Answer
The response has no answer records.
Authority
moh.gov.sg. 900 SOA gccin3psicnsp01.sgnet.gov.sg. root.pridns.gov.sg. 2013211114 10800 1080 2419200 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0