Are magnets involved in mail delivery?

I recently went on a cruise to Alaska, and on returning left my camera at my daughters house. Since I won’t see her again for 2 months, she took the camera chip out of the camera and mailed it to me. The memory chip now seems to be blank.
Do they use magnets while sorting mail? This would explain why the chip seems to be erased. It was a new camera, so I suppose it is possible that the chip has to be in the camera to be read.