They are only closed for the public holidays and the rest of the time is normal working days.

There is also the posties holiday but don't know which day that is.

There is also the posties holiday but don't know which day that is.

that is usually the 27th

http://auspost.com.au/about-us/christmas-and-new-year-holiday-services-2012.html

The date selected for the Australia Post Authorised Holiday over the 2012-2013 Christmas / New Year period is Monday 31 December 2012.

Thank you, that's just the link i was looking for.

Oh, good that is better  🙂

Item purchased on 22-Dec-12 after 12:30 with a message saying...

Would it be possible if you could post it today?

What would you reply?

My reply would be - "Yes I can but it won't go anywhere until after 6.00 pm tomorrow":-)

Australian buyer? 

I'd respond and thank them for purchase/payment, notify of exact postage date, inform of AP holidays and ask to please allow for delays, then thank them in advance for their patience and understanding. (That's assuming they didn't select any kind of Express option, perhaps indicating they were thinking it'd arrive on Monday).