postal-logistics

Intelligent Mail Barcode (IMb) (USPS IMb)

65-bar 4-state height-modulated barcode mandated by the United States Postal Service for sorting and tracking domestic letters, flats, and business reply mail.

Governing Specification: USPS-B-3200

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Data Format & Required Fields

Encodes 31 digits of mail piece tracking and routing data using 65 vertical bars, each having four possible height states (tracker, ascender, descender, full bar).

Allowed Character Set20, 25, 29, or 31 numeric digits (Barcode ID, Service Type, Mailer ID, Serial, and Routing ZIP code).

Payload Length Rule Between 20 and 31 characters

Example Valid Format0123456709498765432101234567891

Industry Guidance & Practical Applications

USPS domestic letters, bills, and marketing mail automation
Qualified Business Reply Mail (QBRM) and Address Element Correction
Informed Delivery parcel and envelope tracking

Packaging & Scanning Notes: Replaced legacy POSTNET and PLANET symbologies in USPS automated operations.

Symbol Constraints & Label Guidelines

Height-modulated bars require specialized postal optical scanning equipment.
Cannot be verified using standard 1D linear laser barcode readers.