What happens if a presorted parcel is mailed without an IMpb?

When a presorted parcel is mailed without an Intelligent Mail package barcode (IMpb), it cannot be processed as a presorted item. The IMpb is crucial for the USPS to sort and track packages effectively, as it contains important information about the shipment, including its service level and whether it qualifies for presorted pricing. Without it, the package cannot be recognized as presorted and therefore loses its eligibility for the associated discounted rates. As a result, the mail will be charged non-presorted prices, which are typically higher. This reflects the USPS's policies on pricing and processing based on proper labeling and barcoding practices.