Have you checked and deleted your email in your mailbox? It is apparently full and past the quota so any time mail is sent to you, it bounces and this triggers Aus-City to think you are no longer at that address and therefore it bans you as you need a viable email address to be a member here.

So check your mail and then delete some of the messages to make room. Or else get another/new email address. But I'd just clear out my current mailbox if I were you.