R.B.
I got a cake once that had been shipped. It had been frozen and then sprinkled with powdered sugar and wrapped in saran wrap and then in tinfoil, packed in a box with plastic bags to protect it from bumping around. The outside of the box also had a this side up arrow. It was shipped next day to me so I think that is why it was still fozen in the middle. It was excellent, but like I have read below it was a heavier cake with a heavy frosting. I think it was butter cream, but not sure. I have also seen them shipped with that fondant icing.
Good luck and hope this helps