First of all, I'm really sorry you are having trouble signing up.
I've done some digging and it seems like there is an issue with any of the Microsoft email services (Hotmail, MSN, Outlook etc) that have blocked all of ProBoards (they company that hosts our forum) activation emails.
They have their tech's looking into a workaround but until then it seems the only way to create a new account is to use an email address from one of the other email providers such as Gmail or Yahoo.
Unfortunately there is no way we can authorise your new account at this end either and this is happening to all ProBoards forums, not just Ausprep.
I will keep monitoring this and can drop you an email when ProBoards and Microsoft have sorted this out if you don't want to use a different email address.
Wolves don't lose sleep over the opinions of sheep.