A cat was "very lucky to survive" after she was accidentally put in the post and trapped in a box for eight days.
Cupcake climbed into a box of second-hand cds and dvds which was sent on a 260-mile journey from Cornwall to West Sussex.
The eight year-old Siamese, who was dehydrated and very hungry when she was found, has since been returned to her owner.
RSPCA inspectors were called on Tuesday after a company discovered the cat in the box which had been mailed from Falmouth to Goring-by-Sea.
She was taken to the vets, where her microchip was scanned.
RSPCA inspector Julie Parsons said: “Poor Cupcake was very lucky to survive.
“When I arrived she was very weak and fragile. She had been trapped in the box for around eight days and was in a dehydrated and very hungry state.
“Luckily, she made a quick recovery, and had been microchipped so I was able to scan her and track her owners down.
“I couldn’t believe it when I found out they were all the way down in Cornwall - what a distance.
"A proper travelling cat. I never would have thought of putting a ‘Pet Found’ poster up down there."
Cupcake's owner, Julie Baggott, told BBC South Today that it was a "miracle" that her cat survived.
“I feel terrible about what’s happened, you know," she said.
"I mean, I put everything in the box and I sealed it straight away, so I don’t know how she managed to get in there."
Parsons added: “It just goes to show how important it is to microchip your pets, and keep the details updated.
"Without this there is no way I would have known where she came from and her owners might still be frantically searching for her.”