As of February 10, 2018 Sandboxx Letters no longer include a pre-stamped return envelope.
Sandboxx lets our friends & family back home send physical post mail directly from their mobile device. Sandboxx users can take a photo, add text, click send, and it is printed, folded, and sent in the mail. Letters also include a pre-addressed envelope to go back to the sender. Supporting your service member is the core of our mission.