SPF3.esker.com.au has no MX records.
Question and response
Question
dig SPF3.esker.com.au. MX
Answer
The response has no answer records.
Authority
esker.com.au. 10800 SOA ns1.gandi.net. hostmaster.gandi.net. 1771459200 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0