Please do not remove the original from it’s frame or mounting. This can damage the image.
If the photo is covered by glass then wrap with bubble wrap and mail in a cardboard box. FedEx standard boxes are usually a good option.
If the photo is loose then cover with ordinary kitchen parchment paper, place on a cardboard backing for support and mail in a box.
Please send via Fedex, UPS or USPS WITH a tracking service.
