mail01.access4.com.au has no CNAME records.
Question and response
Question
dig mail01.access4.com.au. NS
Answer
The response has no answer records.
Authority
access4.com.au. 566 SOA ns-10.awsdns-01.com. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0