We have been informed that using Care of Australia post to have your parcels sent to, is not an acceptable option. This comes directly from Aus post as they have said the only time you can do this is if you do not have a permanent address.
So it is up to the discretion of the post office whether they will sign for the parcel.
We have already had 1 order returned to us due to the post office not wanting to accept it.
So how do you get around this so you can still use care of? You will need to call the local post office before placing your order and addressing it to them. If they say they can do it, then all is well, otherwise address it somewhere where you can sign for it yourself, which is the best option and one we always prefer to have done.
Out side of this, we have started using the "Do not safe drop" stickers on all australia post orders so that they all get carded if no one is home.