What items require a barcode?

Parcels, packages, and Priority Mail® Express or Priority Mail® pieces of any shape, size, or price category, including flat-rate boxes and envelopes require an IMpb (barcode). In addition, the following mail classes require an IMpb: 

  • First-Class Mail Package Services
  • Parcel Select
  • Parcel Select Lightweight
  • Standard Mail
  • Library Mail
  • Media Mail
  • Bound Printed Matter