Sending 8x10 photos through the small safely requires a few supplies: cardboard backing, painter's tape, and envelopes. A sturdy piece of cardboard backing is essential for keeping your photos from being bent or folded. Amazon carries 8x10 pieces that can be secured to a photo by painters tape which doesn't damage the photo when removed. The outer envelope will need to be 9.5x12.5 inches while the inner return envelope will be 9x12 inches. Pack your SASE, LOR, and photo in the larger envelope and send it off!