The process is simple and costs your inmate nothing on their end.
Every letter and postcard sent through InmateAid includes InmateAid's Florida address as the return address on the envelope. When your inmate wants to write back, they simply address their reply to that Florida address and mail it out through the facility's regular outgoing mail using a postage stamp. That stamp is the only thing it costs them, and indigent inmates who have no money on their books can typically get stamps provided by the facility for basic correspondence.
On your end, when the reply arrives at InmateAid's Florida office it gets scanned and uploaded to your account as a PDF. You receive an email notification letting you know incoming mail is waiting, then log in and retrieve it from your dashboard. The fee for that incoming letter retrieval is $1.49 per letter.
The complete exchange works like this. You pay to send, your inmate pays only for a stamp to reply, and you pay $1.49 to receive their scanned letter through your account. Your home address stays completely private throughout the entire process because your inmate is writing to InmateAid's address rather than yours.
It is a straightforward system that keeps communication flowing in both directions without requiring your inmate to have any account, any technology access, or any money beyond a single postage stamp. Everything else is handled on your end through your InmateAid dashboard.