GLOSSARY
Intelligent Mail barcode
By Justin Winter · Updated August 28, 2026
The USPS barcode printed on letter mail that encodes routing and a unique piece identifier, enabling automation rates and tracking.
The Intelligent Mail barcode (IMb) is the row of tall and short bars along the bottom of a letter. It carries the destination routing code plus identifiers for the mailer and the individual piece.
Because each piece is uniquely identified, USPS scans can be tied back to a specific mailing — which is what makes tracking and delivery visibility possible on automated letter mail.
See also
- USPS Marketing Mail — The bulk advertising class, formerly Standard Mail: cheaper per piece, but it requires a permit, a minimum volume, presorting, and it travels slower.
- Address standardization — Rewriting an address into the exact form USPS uses — canonical abbreviations, directionals, unit designators, and ZIP+4.
- Certified Mail — A USPS extra service that adds a dated mailing receipt and delivery tracking to a letter, with the delivery record kept by USPS.
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