What must be present on the Postal Money Order to make it valid?

To validate a Postal Money Order, it must include certain essential elements that confirm its authenticity and ensure it can be processed correctly. Among these requirements, having a printed serial number is crucial. The printed serial number uniquely identifies each money order, enabling tracking and verification in the postal system. It helps protect against fraud and ensures that the money order can be traced back if necessary.

While other features, such as security features and signatures, play important roles in the integrity and verification processes, the printed serial number is a fundamental requirement that directly contributes to the legitimacy and validity of a Postal Money Order. Therefore, the presence of this printed serial number is what makes the money order valid and functional within the postal service system.