My son researched this before he went to Great Lakes- He came upon a neat app called Sandboxx. - It is easy to understand as it walks you through the process of writing to your service member - of any branch... It is something you have to pay for - so this may be kicked off of the the forum.. but I and my family have used this to send and receive letters to our son - at RTC and now at Pensacola. It provides your letter to him/her and then provides space for them to write you and a self addressed envelope!! I typically will type or even dictate into my phone and it transcribes it into the field -counting the number of characters- up to 3000. It counts down the characters - so you don't go over, and so you fill up the page- as the recruit is starving for information about home and the outside world. Our son loved the info about the Olympics! Sandboxx then prints it out and sends it - in a day or two. You can even add a photo!! Anyways - I thought this may help folks actually send letters as someone does the drudgery of putting words on paper and stamping and sending it.