InmateAid's letter mailing service is designed to make communication easier on you as you can do it all from a smartphone or computer. Jails and prisons do NOT allow self-addressed stamp envelopes past the mail room. The rule is for the inmate to purchase stamps and writing utensils from the commissary.
https://www.inmateaid.com/ask-the-inmate/it-is-easier-to-send-mail-through-inmate-aid-or-through-us-postal-can-you-send-a-envelope-and-a-stamp-inside-a-letter-you-are-sending.amp#answer
Accepted Answer Date Created: January 21,2013