That is why InamteAID's letter service is so widely used - the address on our mail is our office in South Florida. If you do not have the return address the mail will likely get returned unopened.
https://www.inmateaid.com/ask-the-inmate/i-need-to-send-an-inmate-a-letter-but-i-don-t-want-to-put#answer
Accepted Answer Date Created: December 12,2015