The administrators have contacted the entity responsible for the blacklisting to de-list the server, unfortunately this process can take some time, in my experience on average it can take 5-7 days however in some rare cases it can take longer.
In the meantime as a temporary workaround you can use your email programs such as Outlook or Apple Mail with your Internet Service Provider's ( mail.bigpond.com.au, mail.optusnet.com.au ) outgoing mail servers.
We apologise for any inconvenience caused.
Please change your outgoing mail server to use your ISP SMTP server.
A list of these can be found at:http://www.homepagecentre.com/hosting-guide/171/outgoing-smtp-mail-servers-of-major-australian-isps.html
They all use port 25 with no SSL and no authentication.