What happens to mail that is not forwarded after the forwarding duration has expired?

When the forwarding duration has expired and the mail is no longer eligible for forwarding, the appropriate action taken is to return it to the sender. This ensures that the sender is informed of the mail's failure to reach the intended recipient, allowing them to take necessary actions if needed, such as updating the recipient's address or resending the item.

Returning the mail allows for proper communication between the senders and recipients, maintains the integrity of the mailing process, and ensures that undeliverable items do not clog the mailing system. Effective management of undeliverable mail is essential for the efficiency of postal operations and customer service.