How long are certified mail pieces held at the post office before being returned?

Certified mail pieces are held at the post office for 15 days before being returned to the sender. This policy allows recipients time to pick up their mail, often giving them a reasonable period to be aware of and act upon the delivery. The 15-day holding policy is designed to strike a balance between allowing sufficient time for notification and ensuring that undelivered or unclaimed certified mail is returned to the sender in a timely manner. Other durations like 10, 30, or 45 days do not align with USPS guidelines for certified mail, making the 15-day period the correct answer.