How To Write An Inmate Letter . If you cannot find a mailing address, call the facility and ask them to give you the correct address. Be sure you include a full return address. Inmate Letter 2 Prison Meditation Network from authorjamesbishop.com Don’t put perfume on the letter. If you decide that you would like to strike up a pen pal relationship with an inmate, you should do some research first and perhaps set some ground rules for yourself. Here are our best tips on how to write a letter to an inmate: