How Long to Wait for Tenant Response to Claim on Security Deposit

[Jason L.]

I sent notice to a previous tenant on making a claim on their deposit recently. I sent the notice via Certified Mail to the address the tenant gave me. The tenant was not home at the time of delivery of June 20. USPS transported the letter to the local Post Office the same day, but the tenant has still not picked up the letter as of today, the 25th. By Florida landlord law, the tenant has 15 days to respond to my claim after receiving the letter, meaning they would have until July 5th. However, I don't know how the law reflects when a tenant was not home for the delivery and has not picked up the letter from the Post Office.

I'm sure some other landlords have experienced this before. Assuming the tenant does not pick up the letter from the PO, when would I be required to send them back the remainder of their deposit?