From the time you send a letter through InmateAid, expect it to reach the facility's mailroom within two to three business days via USPS. Once it arrives it goes through the standard mail inspection process before being handed out at mail call, so factor in an additional day or two depending on how busy the mailroom is at that facility.
On the response side, yes, your inmate can absolutely write back. InmateAid's return address is printed on the outgoing envelope, and your inmate can use that address to send their reply. The letter comes back through InmateAid on your behalf, which means your personal home address never has to be shared with the facility or appear on any mail going in or out of the prison.
This is one of the features that InmateAid members genuinely appreciate. Full two-way correspondence is possible while keeping your personal information completely private. For people who prefer not to have their home address in the facility's system, or who simply want that layer of separation, it is a meaningful benefit that standard mail does not offer.
The round-trip timeline for a full exchange, your letter going in and their response coming back, runs about a week to ten days depending on mail call schedules and how quickly your inmate responds. Staying consistent with letters is the best way to keep that back and forth moving.