It is a physical letter that is sent via USPS. The inmate gets to hold it in their hands. It is especially rewarding when they get pictures in that envelope at mail call, too
https://www.inmateaid.com/ask-the-inmate/was-wondering-if-the-inmate-gets-the-letter-like-a-regular-letter-or-do-they-have-to-log-in-to-a-account-to-see-if-a-letter-has-been-sent-to-them-how-i-know-the-inmate-got-the-letter#answer
Accepted Answer Date Created: May 07,2019