deadlettering

Deadlettering is the process by which mail that cannot be delivered to the intended recipient or returned to the sender is handled by a postal service. It covers letters, parcels, and other mail pieces. Causes include missing or illegible addresses, incorrect or insufficient postage, forwarding not available, or the recipient moving without a forwarding address. Some mail may be addressed to a deceased person or to an institution.

When mail is undeliverable, postal systems first attempt to determine the addressee or return to the sender if a return address exists. If the item cannot be redirected, it is sent to a dedicated unit known in many countries as a dead-letter office or mail recovery center. Authorized staff may inspect the exterior to identify addresses, labels, or other clues while complying with privacy rules; contents are typically not opened except as necessary to identify the recipient or the sender, and only by authorized personnel. The goal is to locate a legitimate recipient or to return the item to the sender.

If no owner can be found, the mail may be kept for a finite period, then disposed of or donated according to policy and privacy laws. Some items containing cash or valuables may be handled by separate procedures, including reporting to authorities or surrender to the treasury. In many countries, the institution is the Mail Recovery Center, Dead Letter Office, or similar.

Historically, postal systems operated a Dead Letter Office to recover misaddressed mail; the term dead letter remains used in postal history and philately as a descriptor for undeliverable mail. In contemporary practice, the function remains essential for reducing loss and protecting privacy, even as the term shifts toward undeliverable mail.