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Intelligent Mail Container Barcode

The Intelligent Mail Container barcode, or IMcb, is a barcode on mailer-generated pallet labels that identifies each pallet or similar container and its mail owner. It ties each container to one mailing, so USPS can track it as it is loaded and unloaded. It holds 21 characters, printed as a GS1-128 or a GS1 DataMatrix barcode.

Updated October 28, 202621 sources

What it is

The IMcb labels a container, the unit load of mail: a pallet, a container or rolling stock. It goes on pallets and on similar containers such as all-purpose containers, hampers and pallet boxes.

The IMcb gives USPS visibility of mail at the level of the container. It links the electronic mailing record to the physical container. It names the mail owner, mail preparer or consolidator through its Mailer ID field.

USPS and approved vendors must use the IMcb specification for systems that produce, read, decode and transmit IMcb data. Suppliers must meet every requirement of the documents the specification cites, listed or not. When the specification and a cited document conflict, the specification's text takes precedence. The label printing entity is responsible for the quality of the labels it produces.

Among the other Intelligent Mail barcodes, the Intelligent Mail barcode sorts and tracks letters, cards and flats. The Intelligent Mail tray label identifies each tray, tub and sack.

How it works

The mailer prints the IMcb on the pallet label, and USPS scans it at acceptance and at points through transportation and processing. The label also carries text naming the mail owner, the destination and the type of mail.

In eInduction, USPS checks payment and preparation of commercial mail containers with the IMcb, the mailing's eDoc and handheld scanners.

The IMcb's part in an eInduction mailing, from preparation to verification.

  1. The mailer puts an IMcb, unique and not reused for at least 45 days, on each container.
  2. In the eDoc, each container's barcode must begin with 99M.
  3. The PostalOne! system checks that the IMcb is present and valid before releasing the container.
  4. At induction, the Surface Visibility system scans the barcode and checks the container's payment record.
  5. The PostalOne! system compares the induction scans with the eDoc to verify payment and preparation.

The data string

Every IMcb encodes 21 characters in one of two layouts, and the Mailer ID's length picks the layout. The Mailer ID is the six- or nine-digit number USPS assigns to identify each mailer.

Both layouts hold four fields in the same order, and only the Mailer ID and serial number lengths differ.

FieldCharactersPositions, 6-digit Mailer IDPositions, 9-digit Mailer ID
Application IdentifierNumeric1-21-2
Type IndicatorAlpha33
Mailer IDNumeric4-94-12
Serial NumberAlphanumeric10-2113-21

In an eInduction eDoc, the barcode must begin with 99M and must be 21 characters long. The Mailer ID in it must be numeric.

The mailer defines the serial number. Any letters in it must be uppercase. USPS recommends leading zeros to fill a serial number shorter than its field.

The USPS layout drawing for a 6-digit Mailer ID prints the human-readable line as 99 M 123456 -----ABC1234.

Printing it

Both formats go on the front of the pallet label, as USPS drawing 1056370 shows. Both print the data as human-readable text, centered 0.125 to 0.25 inch under the barcode. That text is bold sans serif, at least 12 point. The banner over the barcode reads USPS SCAN REQUIRED on the layout drawings.

RequirementGS1-128GS1 DataMatrix
ShapeLinear, one-dimensionalA 20x20 square symbol
Height0.75 to 1.1 inchesSet by the matrix size and the X-dimension
LengthAt most 7.25 inchesSet by the matrix size and the X-dimension
Clear zone10 times the X-dimension left and right, 0.125 inch above and below0.10 inch on all four sides
BannerBold sans serif, at least 14 point18-point reverse type

The linear format also has black identification bars, at least 0.10 inch thick, over and under the barcode.

A printer must print at least 203 dots per inch, and 300 or more is recommended. The symbol contrast must be greater than 40 percent. Reflectance must be measured with a USPS-specified reflectance meter or barcode verifier.

Rules

The IMcb must consist of a 21-character data string encoded as either a linear, one-dimensional GS1-128 or a two-dimensional GS1 DataMatrix barcode.

Every IMcb must hold exactly 21 characters. The mailer must print them as a GS1-128 barcode or as a GS1 DataMatrix symbol.

Moreover, mailers must encode alpha characters as UPPERCASE characters (i.e., all letters are capitalized), matching the values provided to the Postal Service in any other medium (physical or electronic), e.g. Mail.dat, Mail.XML, or Shipping Services File.

The mailer must print every letter in uppercase. The barcode must match the value the mailer sends USPS in its eDoc or other files.

Should be unique within the 45-day period across all jobs from the postage statement mailing date

In an eInduction eDoc, each IMcb should be unique across all jobs for 45 days from the postage statement mailing date.

Label or placard size and print layout for the IMcb must comply with the DMM, this specification, and USPS drawing 1056370 Label, Container, Intelligent Mail.

The label's size and layout must follow the Domestic Mail Manual, the IMcb specification and USPS drawing 1056370.

Mailers must ensure that Subset A is not inadvertently used.

A GS1-128 IMcb must use only Code 128 subsets B and C. Mailers must check that their software does not switch to subset A.

The human readable interpretation of the data characters represented in the barcode must be displayed.

The label must show the barcode's characters as text people can read.

What goes wrong

The PostalOne! system sends Surface Visibility an electronic e8125 or e8017 record for each container it releases. A container with no such record, because of a validation or payment issue, is not expected and needs resolution.

Surface Visibility detects an IMcb scanned more than once in the same appointment. The user then decides whether a duplicate placard or a repeated scan caused it. When one barcode is on several pallets, the first container is accepted and the others are rejected as duplicates.

At a site without Surface Visibility, scanners only collect data and accept every barcoded container. After induction, the PostalOne! system logs an error for each verification a container fails. Two of those errors are about the IMcb:

  • An Undocumented error, when a scanned IMcb is in no eDoc, or is in one tied to a postage statement in EST status.
  • A Duplicate error, when the same IMcb is on two or more containers within 45 days of the postage statement mailing date.

With special approval and registration, USPS lets a mailer induct containers before paying postage by issuing it a Continuous Mailer ID. Any container whose IMcb holds a continuous Mailer ID is accepted when scanned at the dock. Continuous mailers have a 10-day grace period to upload the eDoc after the container is scanned.

Terms

Containermail container
the term used to describe the mail containers (pallet, Gaylord, all-purpose container, etc.) used to carry an aggregate of handling units
Mailer IdentifierMID, Mailer IDs, Mailer Identification, Mailer Identification Number, USPS Mailer ID
MID is a unique 6- or 9-digit number that identifies the mailer or the mailer’s client.
GS1 Application IdentifierAI, Application Identifier
GS1 Application Identifiers are a specific set of defined identifiers used to connect physical and logical things to information or business messages related to them. This field of two or more characters at the beginning of an Element String uniquely defines format and meaning of the string.
GS1-128 Barcode SymbologyGS1-128
A subset of the more general Code 128 that is utilized exclusively for GS1 System data structures.
GS1 DataMatrix
A special type of DataMatrix barcode conforming to a structure defined byGS1.
Human-Readable TextHR, Human-Readable Interpretation, Human-Readable
The letters and numbers that represent the information encoded within a barcode.
X-dimension
The nominal width of the narrowest bar or space element within the barcode symbol is defined as the X-dimension.
Quiet Zoneclear zone
A clear space with no encoded information that precedes the Start Character of a barcode and follows the Stop Character. Formerly referred to as “Clear Area” or “Light Margin.”
Symbol ContrastSC
Difference between the highest reflectance value and the lowest reflectance value anywhere in the scan reflectance profile, including the quiet zones.
eInductionEIN, electronic Induction, eInduction program, eInduction Pilot program
The electronic Induction (eInduction) process streamlines the preparation and induction (how and where the mail physically enters the USPS mailstream) of drop shipments and expedited plant load mailings.
continuous mailer
mailers that have continuous mailing sites and that deliver shipments within 2 hours of finalization

Documents

Tech Guides

Technical Specifications

User Guides

Contacts

Questions about the IMcb go to the IM Container Barcode Program Manager, 8403 Lee Highway, Merrifield, VA 22082-8101. Mailers without a Mailer ID, or with questions about one, should contact their USPS account representative or the PostalOne! helpdesk at (800) 522-9085.

Sources