Found serious SOA errors here:
Host name wXw.opticalwarehouse.com.au refers to a CNAME.

The host name is an alias (CNAME), which is not allowed. Host names must be published with an A or AAAA record.
Error while checking SOA MNAME for opticalwarehouse.com.au (wXw.opticalwarehouse.com.au).

The SOA MNAME was not a valid host name.

Delivery over IPv4 to root@opticalwarehouse.com.au could not be done.
Failed to deliver email for SOA RNAME of opticalwarehouse.com.au (root.opticalwarehouse dot com.au) using root@opticalwarehouse.com dot au.

DNSCheck failed to deliver email to the email address listed as the one responsible for the zone.

Re: http://dnscheck.pingdom.com/?domain=opticalwarehouse.com.au&timestamp=1406672990&view=1

polonus