A mailing receipt is a document provided by postal services that confirms the acceptance of a package or letter for delivery. It typically includes details such as the date of mailing, the sender's information, and a tracking number. This receipt serves as proof that the item was sent and can be used to track its status during transit. When sending important documents or packages, keeping the mailing receipt is essential. It can help resolve any disputes regarding delivery and provides a reference if the item is lost or delayed. Many postal services, like USPS or FedEx, offer online tracking using the receipt's tracking number.