No idea, but the same has happened to me - but usually going from WA to QLD. The item (express post or parcel post bag) has gone over to the other side of the country, then been returned, despite the address being 100% correct.
The last time I got a free express post bag out of it, but that was a small compensation for all the time spent by myself and the recipient sorting out where it was and what the problem was.
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