# Package labels and tracking numbers (IMpb)

A domestic USPS tracking number names the package's channel, service and mailer, then numbers the piece.[^1][^2][^3] The label's [Intelligent Mail Package Barcode](https://postalref.com/products/impb.md), or IMpb, holds it, preferably joined to the routing ZIP Code every label must carry.[^1][^4] The label also shows the service with its postage, both addresses and an [Intelligent Mail Matrix Barcode](https://postalref.com/products/intelligent-mail-matrix-barcode.md), or IMmb, with the same data.[^5][^6][^7]

Updated November 6, 2026. 62 sources.

## Questions

### What do the numbers mean in a USPS tracking number?

In a domestic USPS tracking number, the first two digits name the channel, the next three the service, and the rest the mailer and the piece.[^1][^2] The Service Type Code names the mail class, product and extra services, and the [Mailer ID](https://postalref.com/products/mid.md) names the mailer.[^1][^3] The serial number stays unique for 120 days, and the check digit is computed from the digits before it.[^1][^8]

### How many numbers are there in a USPS tracking number?

A commercial USPS tracking number has 22 or 26 digits, depending on the length of its serial number.[^9][^10][^11] In the `C01` construct, for example, a 2-digit channel application identifier, a 3-digit Service Type Code, a 9-digit Mailer ID, a 7-digit serial number and a check digit make 22.[^9] Shippers with a 9-digit Mailer ID use a 7- or 11-digit serial number, and those with a 6-digit one a 10- or 14-digit serial number.[^12] The whole barcode holds 22, 26, 30 or 34 digits, longer when it also holds the routing ZIP Code.[^12] Every package must carry that routing ZIP Code, in the IMpb or in a separate routing barcode.[^13]

### What does a USPS tracking number look like?

A USPS tracking number prints in groups of four digits, such as `9212 3912 3456 7812 3456 70`.[^4][^14] It prints under the [IMpb](https://postalref.com/products/impb.md) and leaves out the routing application identifier and the ZIP Code that the barcode holds.[^15][^1] Over the barcode, the barcode banner text says whether delivery needs a signature.[^16]

### How do USPS tracking numbers start?

A domestic USPS tracking number starts with its channel application identifier, two digits that name the channel the package came from.[^1][^2] Numbers from online, PC Postage and meter shippers start with `94`, while commercial shippers and USPS retail use other identifiers.[^17][^2] An international shipment's tracking number is a 13-character customs barcode instead, and its first two characters are letters.[^18][^19][^20]

### How big does a USPS shipping label need to be?

USPS prefers the shipping industry's standard 4x6 inch label.[^21] Smaller 4x4 and 6x3 inch labels fit parcels that can't take a 4x6 label.[^21] Every size must meet the same requirements for the IMpb segment.[^21] A [USPS Returns](https://postalref.com/guides/returns.md) label must be 4x6, 4x4 or 3x6 inches and certified by USPS before it is handed out, and any other size needs written approval from the National Customer Support Center.[^22]

### What does a USPS shipping label look like?

On a USPS shipping label, the service icon block should sit at upper left and postage at upper right, with the service banner under both.[^23][^24] On a 4x6 label, the payment and branding, address and IMpb segments sit together, with the shipper's own information at the top or bottom.[^21] Labels should print in black ink on a white background, except the shipper's own segment, which may use color.[^5]

### How long is a USPS shipping label good for?

A [meter or PC Postage](https://postalref.com/products/pes.md) label must be mailed by the date in its postage indicium, or else carry a second mark, a date correction indicium.[^25] Metered mail with a complete date must be mailed that day, but a piece entered after the day's last collection may bear the next one's date.[^25] For a refund of an unused, dated PC Postage label with a tracking number, the user must ask its provider within 30 days of printing.[^25]

### Can USPS print shipping labels for you?

Yes, every USPS platform prints labels with the IMmb, among them retail units, self-service kiosks and Click-N-Ship.[^7] A Post Office can also print a label that a business stored for its customer in [USPS Label Broker](https://postalref.com/guides/shipping-apis.md).[^26][^27] The customer shows the label's QR code or Label Broker ID, and the retail associate prints the label and applies it to the package.[^27]

## How it fits together

The [Intelligent Mail Package Barcode](https://postalref.com/products/impb.md) is a GS1-128 barcode that holds a package's tracking number and, in its preferred form, the routing ZIP Code too.[^1][^4] USPS equipment reads the routing data to sort and track each package to the post office that delivers it.[^28] Every parcel shipped through USPS must carry the IMpb or another unique tracking barcode.[^29]

The tracking number, which USPS calls the Package Identification Code, is unique to each mailpiece.[^30] Its channel application identifier names the channel the package came from and where USPS can find its payment record.[^2] Its three-digit Service Type Code names the package's [mail class](https://postalref.com/guides/mail-classes.md), product and extra services.[^1] A shipper gets its [Mailer ID](https://postalref.com/guides/business-accounts.md) from the Mailer ID tool on the [Business Customer Gateway](https://postalref.com/products/business-customer-gateway.md).[^3] The gateway is USPS's single entry point for its online business services.[^31]

The Parcel Labeling Guide sets out how to design a domestic shipping label for a USPS parcel.[^32] A label's payment and branding segment shows the service and postage, and its address segment holds the return and delivery addresses.[^5][^6] Directly left of the delivery address sits the [Intelligent Mail Matrix Barcode](https://postalref.com/products/intelligent-mail-matrix-barcode.md), a two-dimensional barcode with the same data as the IMpb.[^33][^7]

Each package also needs a version 1.6 or higher [Shipping Services File](https://postalref.com/guides/package-payment.md) record with its details.[^28] USPS then sends the shipper a scan event extract file with [tracking](https://postalref.com/guides/package-tracking.md) information about the package's movement through the mail stream.[^34]

## The barcode and the tracking number

The IMpb is a data string encoded in GS1-128, subset C.[^1] GS1-128 is a kind of Code 128 barcode that uses application identifiers to say what each piece of data is and how to read it.[^35]

The routing application identifier, always `420`, precedes the [destination ZIP Code](https://postalref.com/guides/address-matching.md), which has five or nine digits.[^1] USPS requires a routing ZIP Code on every package label and prefers a concatenated barcode, which holds the ZIP Code and the tracking number together.[^4][^1]

An IMpb begins with a start character and then a Function 1 character, which the human-readable text doesn't show.[^3][^36] In a concatenated barcode, a second Function 1 character after the ZIP Code joins the routing data to the tracking number.[^37]

> The 5digit ZIP Code is required on all packages, either as part of the concatenated barcode or as a separate routing destinations barcode.[^13]

**Must.** Every package must carry its five-digit ZIP Code for routing. When the IMpb leaves the ZIP Code out, the package must carry it in a separate routing barcode.

An illustrative barcode for an online shipper with a nine-digit Mailer ID and a nine-digit ZIP Code.[^38]

`4202210312349400105912345678123451`: 34 digits, format N05.

| Field | Digits | What it means |
| --- | --- | --- |
| Routing | `420` | The routing application identifier, always `420`, before the destination ZIP Code.[^1] |
| ZIP Code | `221031234` | Five or nine digits.[^1] |
| Channel | `94` | The channel application identifier, `94` for online, PC Postage and meter shippers.[^17] |
| Service type | `001` | The mail class, product and extra services.[^1] USPS Ground Advantage: Up to 15.999oz USPS Tracking[^39] |
| Source | `05` | The kind of online source, such as a PC Postage vendor.[^1] |
| Mailer ID | `912345678` | Six or nine digits that name the mailer.[^1] |
| Serial | `12345` | Unique for 120 days.[^1] |
| Check | `1` | A MOD 10 digit computed from the tracking number.[^40] |

- Passes: 34 digits: format N05, a nine-digit Mailer ID and a nine-digit ZIP.[^41]
- Passes: Check digit 1 matches the digits before it.[^42][^14]
- Passes: The nine-digit Mailer ID starts with 9, and a nine-digit one must start with 9.[^43]
- Passes: 001 is in Appendix I, effective 06/24/2026.[^39]

The Mailer ID and serial number are examples.

The channel application identifier names the channel a package came from and tells USPS where to find its payment record.[^2] Shippers must include it in the tracking number.[^1]

| Channel application identifier | Used by |
| --- | --- |
| `92` | Commercial shippers with a nine-digit Mailer ID[^2] |
| `93` | Commercial shippers with a six-digit Mailer ID[^2] |
| `94` | Online, PC Postage and meter shippers[^17] |
| `95` | USPS retail[^2] |

A tracking number with channel application identifier `94` adds a two-digit source identifier, which names the kind of online source.[^1] USPS assigns each PC Postage or meter vendor its own source identifier.[^1]

A USPS retail barcode has no Mailer ID.[^44] Its channel identifier, a separate field from the channel application identifier, names the retail system that printed it.[^44][^45] Retail systems include the Point of Service system, or POS, that Post Office counters use for retail sales.[^46] They also include Self-Service Kiosks, formerly called Automated Postal Centers, or APCs.[^47] A device ID and a Julian date help keep each retail barcode unique.[^48]

Each combination of fields is a barcode construct, named by a three-digit code such as `C01`.[^11] Commercial shippers have ten constructs, and online, PC Postage and meter shippers have ten more.[^11] A construct holds a five-digit, nine-digit or no ZIP Code, and a label whose construct holds none carries a separate routing barcode.[^11][^13] The barcode's length depends on its construct's fields: 22, 26, 30 or 34 digits.[^11][^12]

The check digit is the last digit, a MOD 10 digit computed from the channel application identifier through the serial number.[^40]

- **Routing Application Identifier**, also called ‘420’, Postal Routing Code Application Identifier, Postal Code Application Identifier: “A specific three-digit GS1 Application Identifier used to designate the presence of a Destination Delivery ZIP Code.”[^1]
- **Channel Application Identifier**: “This is a specific two-digit application identifier used to identify both the business induction channel from which the mailpiece originated and to indicate where Postal Service may locate a payment record for the mailpiece.”[^45]
- **Source Identifier**: “This two-digit field identifies the type of online source: PC Postage vendor, postage meter, or an internal USPS system such as Click-N-Ship.”[^1]
- **Serial Number**, also called SN: “Uniquely identifies the mailpiece associated with this Mailer ID.”[^40]
- **Check Digit**, also called MOD 10 check digit: “A MOD10 Check Digit is the final digit in the barcode data string.”[^42]
- **Channel Identifier**: “The Channel Identifier indicates the retail system from which a barcode originated (e.g., POS, APC).”[^45]
- **Device ID**: “This six-digit field is used and encoded in Postal Service-created barcodes. The mailer shall use this field within the retail barcode construct to help maintain uniqueness and help with traceability to an exact printing source.”[^48]
- **Julian Date**: “This field is used and encoded in Postal Service-created barcodes. The mailer shall use this field within the retail barcode construct to aid in establishing uniqueness. A 4-digit, YDDD format will be used.”[^48]
- **Package Identification Code**, also called PIC, Piece Identification Code, tracking number: “A Package Identification Code or PIC is a unique data string that serves as a unique tracking number for a mailpiece. Each PIC will consist of an Application Identifier, service type code, data string that will vary based upon the specific data construct, and a MOD 10 check digit.”[^49]
- **Function 1 character**, also called FNC1, Function 1: “A symbology character used in some GS1 data carriers for specific purposes.”[^3]

## Service Type Codes

A Service Type Code is the three-digit field that names a package's mail class, product and extra services together.[^1] Some codes mark a package with no extra services.[^48] Others mark a special USPS program, such as Open and Distribute.[^48] Each code has a barcode banner text assigned to it, and many codes share one, such as `USPS TRACKING #`.[^16]

USPS publishes the codes in the Intelligent Mail Package Barcode Service Type Code list.[^28] They differ from the [Service Type IDs](https://postalref.com/products/stids.md) in the Intelligent Mail barcode on letters and flats.[^1]

Service Type Codes that include USPS Tracking. Filter them by mail class or extra service.

| Code | Description | Mail class | Banner text |
| --- | --- | --- | --- |
| `001` | USPS Ground Advantage: Up to 15.999oz USPS Tracking | FC | USPS TRACKING # |
| `055` | Priority Mail: USPS Tracking | PM | USPS TRACKING # |
| `116` | Priority Mail USPS Tracking Hazardous Materials | PM | USPS TRACKING # HAZMAT |
| `184` | USPS Ground Advantage: Up to 15.999oz USPS Tracking Hazardous Materials | FC | USPS TRACKING # HAZMAT |
| `209` | USPS Ground Advantage: Up to 15.999oz Hold for Pickup | FC | USPS TRACKING # |
| `249` | USPS Marketing Mail: Heavy Printed Matter Commercial Marketing Parcels USPS Tracking | S2 | USPS TRACKING # |
| `254` | USPS Marketing Mail: Heavy Printed Matter Nonprofit Commercial Marketing Parcels USPS Tracking | S2 | USPS TRACKING # |
| `259` | USPS Marketing Mail: USPS Tracking Insurance <= $500 | SA | USPS TRACKING # |
| `269` | USPS Marketing Mail: USPS Tracking | SA | USPS TRACKING # |
| `346` | USPS Ground Advantage: One Pound or More USPS Tracking | FC | USPS TRACKING # |
| `362` | USPS Ground Advantage: One Pound or More USPS Tracking Hazardous Materials | FC | USPS TRACKING # HAZMAT |
| `367` | USPS Ground Advantage: One Pound or More USPS Tracking Hold for Pickup | FC | USPS TRACKING # |
| `395` | Parcel Select: USPS Tracking Hazardous Materials | PS | USPS TRACKING # HAZMAT |
| `419` | Bound Printed Matter: USPS Tracking | BB | USPS TRACKING # |
| `490` | Media Mail: USPS Tracking | BS | USPS TRACKING # |
| `551` | Library Mail: USPS Tracking | BL | USPS TRACKING # |
| `612` | Parcel Select: USPS Tracking | PS | USPS TRACKING # |
| `704` | USPS Marketing Mail™ Parcel: USPS Tracking | S2 | USPS TRACKING # |

18 codes in the IMpb Service Type Code List, Appendix I, where Extra service codes is 920.

> The additional validation requires that an IMpb must include a valid, unique 3digit STC that accurately represents the mail class, product, and service combination on the physical label affixed to the package.[^34]

**Must.** The Service Type Code in the IMpb must be valid and must match the mail class, product and services the label shows.

> Additionally, the IMpb on the package must also correspond with electronic package level details and Extra Services Code(s) contained within the Shipping Services File (SSF).[^34]

**Must.** The IMpb must match the package details and the [extra services](https://postalref.com/guides/extra-services.md) in the package's Shipping Services File record.

## The label

A shipping label is a transportation document, so it holds only transportation information.[^5] Its design follows the Parcel Labeling Guide.[^32] The guide clarifies the Domestic Mail Manual, Publication 199 and the Intelligent Mail Package Barcode Specification but does not replace them.[^32]

A label should print in black ink on a white background, except in the shipper's own segment, which may use color.[^5] Its fonts must be sans serif and clear enough for USPS optical character recognition equipment.[^5] Images that resemble a stamp, postmark or cancellation mark are prohibited.[^5]

On a 4x6 label, the payment and branding, address and IMpb segments sit together, with the shipper's own information at the top or bottom.[^21]

| Segment | What it holds |
| --- | --- |
| Payment and branding | The service icon block, the service banner and the postage payment area[^5] |
| Address and delivery information | The return address, any endorsements, the retail distribution code, the delivery route code and the delivery address[^6] |
| IMpb | The barcode, its human-readable text, the barcode banner text and identification bars[^50] |
| Additional information and user | The shipper's own shipment information, branding and logos[^51] |

The service icon block should sit in the upper left corner, and postage should appear in the upper right.[^23][^24] The service banner runs under both, with the class of mail and price marking.[^23] A parcel mailed after the date in its meter or PC Postage indicium needs a date correction indicium next to the original.[^25] Only one is permitted on a piece.[^25]

| Service icon | Meaning |
| --- | --- |
| `P` | Priority Mail[^23] |
| `G` | USPS Ground Advantage[^23] |
| `E` | Priority Mail Express[^23] |
| `H` | Hazardous materials[^23] |
| A solid box, or a box with two crossed diagonal lines | Parcel Select, Media Mail, Library Mail, Bound Printed Matter and Marketing Mail[^23] |

> The service icon block is required and must be used in conjunction with the service banner.[^23]

**Must.** Every label must have a service icon block, and it must be used together with the service banner.

The barcode banner text names the services and characteristics of the barcode, and it should be centered over the barcode.[^15] USPS has called this text a service banner too, but on a label the service banner is the class-of-mail line under the service icon.[^45][^23] A [hazardous materials](https://postalref.com/guides/mailability.md) label should add `HAZMAT` to the banner.[^37]

[USPS Ship](https://postalref.com/products/usps-ship.md) labels should include USPS Ship in the banner text.[^16] The Parcel Labeling Guide covers USPS Ship labels, and its section 4.4 sets out the extra markings a USPS Ship Retail Entry label requires.[^52][^53] Its Appendix F shows sample USPS Ship labels for USPS Ground Advantage and Priority Mail Express, in Figures 29 and 30.[^52][^54]

> Mailers must use a “USPS TRACKING #” human-readable banner text above the barcode on items not requiring a signature at delivery, and a “USPS SIGNATURE TRACKING #” banner text above the barcode on items where a signature is required at delivery.[^16]

**Must.** A package that needs a signature at delivery must show the signature tracking banner text over its barcode. Any other package must show the plain tracking banner text.

The human-readable text under the barcode prints the tracking number in groups of four, without `420` or the ZIP Code.[^4][^1] Black identification bars, 1/32 to 1/16 inch thick, should print over the banner and under the human-readable text.[^37]

The IMpb must be at least 3/4 inch tall.[^55] Its [X-dimension](https://postalref.com/guides/intelligent-mail.md), the width of its narrowest bar or space, must measure 0.013 to 0.021 inch.[^55] A clear zone at least ten times the X-dimension must stay empty on its left and right.[^55] USPS recommends a printer of at least 203 dots per inch.[^55]

The 4x6 inch label is USPS's recommended layout, with room for every element and the shipper's own information.[^21] On smaller 4x4 and 6x3 inch labels, a 0.5-inch service icon beside the service banner is recommended.[^21][^56] Every size must meet the same requirements for the IMpb segment.[^21]

The IMmb is a two-dimensional barcode in the GS1 DataMatrix format.[^7] It holds the same data as the IMpb.[^7] It lets USPS still read a package when the IMpb becomes unreadable.[^7] It needs no barcode banner, human-readable text or identification bars.[^57] Every USPS platform prints it, and so can mail service providers, shipping solution vendors and PC Postage companies.[^7]

Every class of parcel mail except Bound Printed Matter NonPresorted must carry both an IMpb and an IMmb.[^58] The required IMmb sits directly left of the delivery address, which may need 3/5 inch more indentation for its clear zone.[^33] A second IMmb in the additional information and user segment is optional but recommended.[^57] On a 6x3 label, the required IMmb may move to the left of the return address.[^57]

- **Parcel Labeling Guide**: “This document has been developed to facilitate the design and creation of domestic shipping labels for parcels shipped via the United States Postal Service (USPS).”[^32]
- **Publication 199**, also called Pub 199: “The Implementation Guide to Intelligent Mail Package Barcode (IMpb) for Confirmation Services and Electronic Payment Systems Mailers provides technical guidance for the implementation of the Intelligent Mail package barcode (IMpb) and file formats.”[^29]
- **Intelligent Mail Package Barcode Specification**, also called USPS2000508, Barcode, Package, Intelligent Mail Specification, Intelligent Mail Package Barcode (IMpb) Specification: “This document provides specifications for generating and printing the U.S. Postal Service (USPS) Intelligent Mail® Package Barcode (IM™ Package Barcode).”[^35]
- **Barcode Banner Text**, also called Banner text, service banner, USPS Banner: “the human-readable text above the barcode”[^16]
- **Human-Readable Text**, also called HR, Human-Readable Interpretation, Human-Readable: “The letters and numbers that represent the information encoded within a barcode.”[^3]
- **Service Banner**: “The service banner is located directly below the postage payment area and service icon block and includes the class of mail and price marking.”[^23]
- **Intelligent Mail Matrix Barcode**, also called IMmb: “An IMmb is a supplemental GS1-DataMatrix (2D) barcode, which is intended to improve package visibility. The IMmb contains the same data as the IMpb barcode, using a space-efficient barcode symbology”[^58]

## What goes wrong

USPS checks each barcode for readability and correct construction, and each label for proper content and use.[^59] A barcode or label that fails gets the noncompliance code `BQ`, for [Barcode Quality](https://postalref.com/products/impb.md).[^59] Barcode Quality checks catch mistakes such as these:[^59]

- A tracking number reused within 120 days with a different destination ZIP Code, weight or Electronic File Number.[^59] That number, in the Shipping Services File's header record, identifies each transmission of an electronic manifest.[^3]
- A Mailer ID in the label that isn't valid and certified.[^59]
- A Service Type Code that isn't valid and active.[^59]
- On a USPS Ground Advantage label, a service icon, service banner or indicia that doesn't match the Service Type Code.[^59]
- A weight outside the range for the Service Type Code.[^59]

Shippers pay a [noncompliance fee](https://postalref.com/guides/package-payment.md) when their noncompliant pieces pass the threshold for Barcode Quality, Manifest Quality or Address Quality.[^60] Assessments for a missing or mismatched [IMmb](https://postalref.com/products/intelligent-mail-matrix-barcode.md) began January 19, 2025, for hazardous materials packages and April 1, 2025, for all others.[^61]

Leaving out the second Function 1 character after the ZIP Code causes a format error.[^37] Improperly applied labels can cause scanning problems and weaken tracking data.[^62] A label belongs fully on the address side, overlapping no side or other label, with no tape or plastic wrap over its barcodes.[^62] Parcels sent without the required barcodes and electronic documentation may be rejected or intercepted.[^60]

## Index: 24 entries

### Identifiers (16)

- [Channel Application Identifier](https://postalref.com/guides/package-labels.md#barcode)
- [Channel Identifier](https://postalref.com/guides/package-labels.md#barcode)
- [Check Digit](https://postalref.com/guides/package-labels.md#barcode)
- [Device ID](https://postalref.com/guides/package-labels.md#barcode)
- [GS1 Application Identifier](https://postalref.com/products/impb.md#terms)
- [GS1 DataMatrix](https://postalref.com/products/intelligent-mail-matrix-barcode.md#terms)
- [GS1-128 Barcode Symbology](https://postalref.com/products/intelligent-mail-matrix-barcode.md#terms)
- [Intelligent Mail Matrix Barcode](https://postalref.com/products/intelligent-mail-matrix-barcode.md)
- [Intelligent Mail Package Barcode](https://postalref.com/products/impb.md)
- [Julian Date](https://postalref.com/guides/package-labels.md#barcode)
- [Package Identification Code](https://postalref.com/guides/package-labels.md#barcode)
- [Routing Code](https://postalref.com/?q=Routing%20Code)
- [Serial Number](https://postalref.com/guides/package-labels.md#barcode)
- [Service Type Code](https://postalref.com/products/impb.md#terms)
- [shipping label](https://postalref.com/?q=shipping%20label)
- [Source Identifier](https://postalref.com/guides/package-labels.md#barcode)

### Documents (4)

- [Intelligent Mail Package Barcode Service Type Code list](https://postalref.com/?q=Intelligent%20Mail%20Package%20Barcode%20Service%20Type%20Code%20list)
- [Intelligent Mail Package Barcode Specification](https://postalref.com/guides/package-labels.md#label)
- [Parcel Labeling Guide](https://postalref.com/guides/package-labels.md#label)
- [Publication 199](https://postalref.com/guides/package-labels.md#label)

### Terms (4)

- [Barcode Banner Text](https://postalref.com/guides/package-labels.md#label)
- [Function 1 character](https://postalref.com/guides/package-labels.md#barcode)
- [Human-Readable Text](https://postalref.com/guides/package-labels.md#label)
- [Routing Application Identifier](https://postalref.com/guides/package-labels.md#barcode)

## Sources

[^1]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=49), page 50: “The tracking number contains all of the following data elements: Channel Application Identifier, Service Type Code, MID, serial number and MOD10 check digit. … Service Type Code (STC): This three-digit field identifies the mail class, product, and/or extra service(s) combination. … Concatenated barcode data constructs across all USPS channels that allow for destination routing information (i.e., ZIP Code) and package identification code (PIC) data in a single barcode … The serial number is required to remain unique for 120 days. … NOTE: The AI (420) and the ZIP Code (5- or 9-digit) are suppressed in the human-readable representation. … The IMpb consists of a data string encoded in a GS1-128 format, subset C. … This field must always be “420” and precedes the Destination ZIP Code. … Destination ZIP Code: This field may be five- or nine-digits in length. … Source Identifier: This two-digit field identifies the type of online source: PC Postage vendor, postage meter, or an internal USPS system such as Click-N-Ship. … Mailer ID (MID): This field may be six- or nine-digits in length. … Customers must include the channel application identifier as part of the tracking number. … The source identifier is used only with Channel Application Identifier “94”. … Source identifiers are assigned by the Postal Service and are unique to each PC Postage or Meter Vendor. … A specific three-digit GS1 Application Identifier used to designate the presence of a Destination Delivery ZIP Code. … This two-digit field identifies the type of online source: PC Postage vendor, postage meter, or an internal USPS system such as Click-N-Ship. … NOTE: Service Type Codes (STCs) for the IMpb differ from the Service Type IDs (STIDs) that are part of the Intelligent Mail barcode (IMb) used for letters and flats.”

[^2]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=33), page 33: “The Channel Application Identifier (AI) is a specific 2-digit application identifier used to identify both the business induction channel from which the mailpiece originated and to indicate where USPS may locate a payment record for the mailpiece. … Valid IMpb Channel Application Identifiers are “92”, “93”, “94”, and “95.” AI “92” and AI “93” are for use by commercial mailers. AI “94” is for USPS online channel mailings and AI “95” is reserved for the USPS retail environment. … Source: For the commercial mailer, always a “92” when used with a 9-digit Mailer ID or “93” when used with a 6-digit Mailer ID.”

[^3]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=473), page 474: “MID is a unique 6- or 9-digit number that identifies the mailer or the mailer’s client. … The Mailer ID tool is the application on the Business Customer Gateway used by customers to obtain MIDs for use in either Confirmation Services or eVS programs. … FNC1 characters typically follow the start character at the beginning of the barcode and are part of the symbology overhead. … A symbology character used in some GS1 data carriers for specific purposes. … The letters and numbers that represent the information encoded within a barcode. … Electronic File Number uniquely identifies the transmission of an electronic manifest, and must be unique for a period of 120-days. It is located in the header record of the Shipping Services File.”

[^4]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=61), page 62: “The IMpb requires all mailers to include a routing ZIP Code on their package labels and prefers the use of a concatenated barcode format. … For all labels (non-concatenated and concatenated), the human-readable representation of the barcode must be parsed in groups of four with any remaining digits grouped at the end.”

[^5]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=7), page 7: “The payment and branding segment of a USPS label consists of three sections: the service icon block, the service banner, and the postage payment area. … All USPS shipping labels should be printed in black ink on a white background with the exception of the additional information and user section which may include color if desired. … The USPS shipping label is a transportation document, and as such, its content is restricted to transportation information. … Fonts must be sans serif (e.g.: Arial, Helvetica, or Verdana) and of sufficient quality to be processed by USPS Optical Character Recognition (OCR) equipment. … Images that resemble a postage stamp, postmark, or cancellation mark are prohibited.”

[^6]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=10), page 10: “The address and delivery information segment consists of the return address, any endorsements, the retail distribution code, delivery route code, and delivery address.”

[^7]: [ Intelligent Mail Matrix Barcode (IMmb)  FAQ Page](https://postalpro.usps.com/mnt/glusterfs/2025-04/IMmb%20FAQ%20Final%20Version%20April%2011%202025.pdf#page=1), PDF page 1: “Currently, the IMmb contains the exact same data payload as our IMpb. … Every USPS platform (Retail Units, Self Service Kiosks, Click-N-Ship, WebTools) prints the IMmb. … The IMmb is a two-dimensional, GS1 DataMatrix barcode used for routing and tracking of packages within the USPS processing network. … The IMmb provides redundancy to recover visibility should the traditional linear IMpb barcode become unreadable. … In addition, Mail Service Providers, Shipping Solution Vendors and PC Postage companies can also print the IMmb.”

[^8]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=34), page 34: “The Mod 10 check digit is calculated using the package identification code (PIC) portion of the data, which includes the channel AI, STC, MID and serial number.”

[^9]: [Intelligent Mail® Package Barcode (IMpb) Specification](https://postalpro.usps.com/mnt/glusterfs/2018-02/BarcodePackageIMSpec.pdf#page=18), page 13: “Human Readable Representation of Barcode Data: 9212 3912 3456 7812 3456 71 (22 digits) … Table 6: C01 - Commercial Mail Construct Format C01 Data Field “420” Postal Routing Code Application Identifier 9-digit Destination ZIP “92” Channel Application Identifier Service Type Code Mailer ID Serial # Mod 10 Check Digit TOTAL … Field Length 3 digits 9 digits 2 digits 3 digits 9 digits 7 digits 1 digit 34 digits”

[^10]: [Intelligent Mail® Package Barcode (IMpb) Specification](https://postalpro.usps.com/mnt/glusterfs/2018-02/BarcodePackageIMSpec.pdf#page=19), page 14: “Human Readable Representation of Barcode Data: 9212 3912 3456 7812 3456 7890 #1 (26 digits)”

[^11]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=50), page 51: “The serial number can also be of varied lengths depending on the barcode construct selected. … Each barcode construct is identified by a three-digit code (e.g., “C01”). … There are ten constructs for commercial mailers and ten constructs for online/PC postage/postage meter shippers. … For example, a 5-digit, 9-digit, or no routing ZIP Code are options for the barcode constructs. … The total length of the barcode will depend on the elements that the shipper includes as part of a valid barcode construct.”

[^12]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=36), page 36: “MID 9 9 9 9 6 6 6 6 6 9 … Serial Number 7 11 7 7 10 14 10 10 14 11 … This variability in length allows the IMpb to be either 22, 26, 30, or 34 digits in length depending upon the channel AI, serial number, and length of the postal code data (ZIP or ZIP+4).”

[^13]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=29), page 30: “The 5digit ZIP Code is required on all packages, either as part of the concatenated barcode or as a separate routing destinations barcode.”

[^14]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=58), page 59: “Example: assume the PIC is 9212 3912 3456 7812 3456 70 … Step 6: The check digit is the smallest number which, when added to the result obtained through step 5, gives a number that is a multiple of 10.”

[^15]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=14), page 14: “The human readable text below the barcode should display the relevant data of the barcode as described below. … The barcode banner identifies the services and characteristics of the barcode. … The barcode banner should be centered above the barcode.”

[^16]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=57), page 58: “Mailers must use a “USPS TRACKING #” human-readable banner text above the barcode on items not requiring a signature at delivery, and a “USPS SIGNATURE TRACKING #” banner text above the barcode on items where a signature is required at delivery. … Appendix I provides the barcode banner text applicable for each Service Type Code. … The barcode banner text should include “USPS Ship” for USPS Ship customers. … the human-readable text above the barcode”

[^17]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=54), page 55: ““94” (used by Online/PC Postage and Meter Mailers)”

[^18]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=37), page 38: “For international mail items, in the Shipping Services File, provide the 24-character Mailer Label Barcode Convention in the Customer Reference Number and the 13-character Customs Barcode in the Tracking Number.”

[^19]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=181), page 182: “13-character barcode includes: • 2 character Service Indicator *A-Z*”

[^20]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=334), page 335: “IMpb required for domestic shipments, but “S10” type barcode is allowed for international shipments”

[^21]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=16), page 16: “The USPS preferred label size is the shipping industry standard of 4x6 inches. … A 6x3 inch and a 4x4 inch label are described herein and are intended to assist shippers by defining smaller formats and sizes that may more readily fit parcels which do not support the standard 4x6 inch label. … On all label sizes, the Intelligent Mail package barcode segment requirements must be adhered to as described in Section 2.4 above. … The 4x6 (4 inches wide and 6 inches high) label is the USPS recommended layout for parcel labels. … With this layout, the payment and branding, addressing, and barcode segments can be grouped together with user specific elements placed at the top and/or bottom of the label. … This layout allows for optimum spacing of all elements and still allows space for additional information and user elements to be defined by the mailer.”

[^22]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=21), page 21: “USPS Returns label standard sizes are 4x6, 4x4, or 3x6 and must be certified by the USPS for use prior to distribution. … All other label sizes require written approval from the National Customer Support Center (NCSC).”

[^23]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=8), page 8: “The service icon block should appear in the upper left-hand corner of the shipping label. … The service banner is located directly below the postage payment area and service icon block and includes the class of mail and price marking. … The letter P indicates Priority Mail … The letter G indicates USPS Ground Advantage … The letter E indicates Priority Mail Express … The letter H indicates hazardous materials … A solid box or a box with two intersecting diagonal lines indicates Parcel Select, Media Mail, Library Mail, Bound Printed Matter, and Marketing Mail parcels. … The service icon block is required and must be used in conjunction with the service banner.”

[^24]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=9), page 9: “Evidence of postage payment should appear in the upper right-hand corner of the label.”

[^25]: [DMM 604: Postage Payment Methods and Refunds](https://pe.usps.com/text/dmm300/604.htm): “Postage meters and PC Postage products are collectively identified as “postage evidencing systems.” … Postage evidencing systems print indicia such as information-based indicia (IBI) or intelligent mail indicia (IMI), to indicate postage payment. … [11-2-26] A date correction indicium is required for any mailpiece not deposited by the date of mailing in the indicium. Only one date correction indicium is permitted on a mailpiece. … The date or period when mailers may deposit or present metered mail for mailing is controlled by the mailing date in the indicia under the following conditions. … Mailpieces bearing a complete date in the indicia must be deposited or presented on that date, except that pieces entered after the day‘s last scheduled collection from the Post Office or collection box may bear the actual date of entry or the date of the next scheduled collection from the Post Office or collection box. … 9.3.10 Unused, Dated PC Postage Indicia With PIC … Requests must be submitted by authorized users to their provider electronically in accordance with procedures available from their provider. … Requests must be initiated for within thirty (30) days of printing the indicia. … On flat-size mail or parcels: Next to the original indicium.”

[^26]: [USPS: Label Broker (for business)](https://www.usps.com/business/label-broker.htm): “Once USPS has approved your shipping system, you can store customers’ prepaid or postage-guaranteed (return) labels in our secure Label Broker repository.”

[^27]: [Domestic Merchant Returns API: User Guide](https://postalpro.usps.com/mnt/glusterfs/2026-07/Merchant%20Returns%20-%20Web%20Service%20and%20API%20Guide%20v2.6%202026-07-20.pdf#page=60), page 60: “It allows customers to print labels using a QR Code or Label Broker Label ID at a USPS® Post Office® or via USPS.com. … The consumer will need to show the Label Broker code to the USPS® Retail Associate at the Retail Counter who will print and apply the linked label to the shipment.”

[^28]: [PostalPro: Intelligent Mail® Package Barcode (IMpb)](https://postalpro.usps.com/shipping/impb): “The IMpb includes the routing information in the barcode which allows the Postal Service to use automated equipment to sort and track packages as they travel through our network to the post offices that will make final delivery at the respective destinations. … Be accompanied by a version 1.6 (or higher) electronic Shipping Services File record populated with required details about the package. … This document provides the updated service type codes for Intelligent Mail® Package Barcodes.”

[^29]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=16), page 17: “The IMpb or unique tracking barcode is required for all parcels shipped through the Postal Service. … The Implementation Guide to Intelligent Mail Package Barcode (IMpb) for Confirmation Services and Electronic Payment Systems Mailers provides technical guidance for the implementation of the Intelligent Mail package barcode (IMpb) and file formats.”

[^30]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=474), page 475: “A Package Identification Code or PIC is a unique data string that serves as a unique tracking number for a mailpiece.”

[^31]: [PostalPro: Business Customer Gateway](https://postalpro.usps.com/BCG): “gives you a single entry point for Postal Service online business services such as: Intelligent Mail Products and Services, Business Mailing Activity and Reports, Scheduling Mailing Appointments, Mailer IDs (MIDs), Incentive Programs and Information, and Shipping Service Programs.”

[^32]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=5), page 5: “This document has been developed to facilitate the design and creation of domestic shipping labels for parcels shipped via the United States Postal Service (USPS). … The Mailing Standards of the United States Postal Service Domestic Mail Manual (DMM) as well as supporting documents such as Publication 199, Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems and USPS2000508, Intelligent Mail Package Barcode (IMpb) Specification are the official sources for the standards described in this document. … The information in this guide is meant to clarify and enhance the information in these documents but does not supersede them.”

[^33]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=12), page 12: “An Intelligent Mail matrix barcode (IMmb) is required in the Delivery Address Section directly to the left of the delivery address. … This may require additional indentation of the delivery address (3/5 inch) to allow for the barcode’s required clear zone.”

[^34]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=17), page 18: “In return, USPS will provide mailers with two types of files: a scan event extract file and a confirmation/error/warning file. … The scan event extract file contains tracking information about the movement of packages through the USPS mail stream. … The additional validation requires that an IMpb must include a valid, unique 3digit STC that accurately represents the mail class, product, and service combination on the physical label affixed to the package. … Additionally, the IMpb on the package must also correspond with electronic package level details and Extra Services Code(s) contained within the Shipping Services File (SSF).”

[^35]: [Intelligent Mail® Package Barcode (IMpb) Specification](https://postalpro.usps.com/mnt/glusterfs/2018-02/BarcodePackageIMSpec.pdf#page=6), page 1: “GS1-128 barcodes, formally known as UCC/EAN-128, are a special type of Code 128 (ISO/IEC 15417) barcodes that use Application Identifiers (AIs) to define the encoded data and how to interpret it. … This document provides specifications for generating and printing the U.S. Postal Service (USPS) Intelligent Mail® Package Barcode (IM™ Package Barcode).”

[^36]: [DMM 204: Barcode Standards](https://pe.usps.com/text/dmm300/204.htm): “The FNC1 numeric character for GS1-128 follows the symbol start character, is part of the symbology overhead, and is not shown in the human-readable text.”

[^37]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=39), page 39: “Concatenated barcodes use a second Function 1 (FNC1) character immediately following the ZIP Code to join the routing information with the traditional PIC. … When creating labels for packages which will carry hazardous materials, the text “HAZMAT” should be appended to the IMpb banner. … Horizontal black lines with a thickness within the range of 1/32 to 1/16 inch thick should be printed above the USPS Banner and below the human readable representation of the IMpb data. … Accidentally omitting this character will cause a format error.”

[^38]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=55), page 56: “Below is an example of an Online Mailer IMpb construct. The example below describes a construct for a customer using a 9-digit MID and a 9-digit ZIP Code in the label ID.”

[^39]: [Updated List: Service Type Codes for Intelligent Mail® Package Barcode (IMpb)](https://postalpro.usps.com/mnt/glusterfs/2026-06/Service_Type_Codes_Appendix_I_06242026.xlsx), Effective June 24, 2026, code 001: Code: 001; Description: USPS Ground Advantage: Up to 15.999oz USPS Tracking; Mail class: FC; Banner text: USPS TRACKING #; Extra service codes: 920

[^40]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=35), page 35: “A 1-digit, Mod 10 Check Digit is the final digit in the IMpb data string calculated using the package identification code portion of the data, which is the string from the channel AI through the serial number. … Uniquely identifies the mailpiece associated with this Mailer ID.”

[^41]: [Intelligent Mail® Package Barcode (IMpb) Specification](https://postalpro.usps.com/mnt/glusterfs/2018-02/BarcodePackageIMSpec.pdf#page=33), page 28: “Table 21: N05 - Online / PC Postage Label Construct”

[^42]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=51), page 52: “Calculate the check digit using the PIC portion of the data, which does not include the Postal Routing Code Application Identifier and Destination ZIP Code if included. … A MOD10 Check Digit is the final digit in the barcode data string.”

[^43]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=27), page 28: “A six-digit MID must begin with 0–8 • A nine-digit MID must begin with 9”

[^44]: [Intelligent Mail® Package Barcode (IMpb) Specification](https://postalpro.usps.com/mnt/glusterfs/2018-02/BarcodePackageIMSpec.pdf#page=17), page 12: “For example, commercial barcodes will always include the Mailer Identifier, while Retail barcodes will not include the mailer identifier, but will include a channel identifier to indicate the exact system from which the barcode originated.”

[^45]: [Intelligent Mail® Package Barcode (IMpb) Specification](https://postalpro.usps.com/mnt/glusterfs/2018-02/BarcodePackageIMSpec.pdf#page=9), page 4: “The Channel Identifier indicates the retail system from which a barcode originated (e.g., POS, APC). … This is a specific two-digit application identifier used to identify both the business induction channel from which the mailpiece originated and to indicate where Postal Service may locate a payment record for the mailpiece. … A service banner shall be printed in all uppercase letters centered above the barcode.”

[^46]: [Publication 32: Glossary of Postal Terms](https://postalpro.usps.com/mnt/glusterfs/2016-04/pub32_glossary.pdf#page=168), PDF page 168: “The primary hardware and software system used to conduct retail sales transactions in Post Offices.”

[^47]: [USPS news release: Post Offices Closed Monday, Nov. 11 to Observe Veterans Day (Vermont, Nov 2013)](https://about.usps.com/news/state-releases/vt/2013/vt_2013_1107.htm): “But some post offices which have Self-Service Kiosks (SSKs), formerly known as Automated Postal Centers (APCs), provide mailing services to customers using a credit or debit card 24-hours a day, 365 days a year.”

[^48]: [Intelligent Mail® Package Barcode (IMpb) Specification](https://postalpro.usps.com/mnt/glusterfs/2018-02/BarcodePackageIMSpec.pdf#page=10), page 5: “The mailer shall use this field within the retail barcode construct to help maintain uniqueness and help with traceability to an exact printing source. … The mailer shall use this field within the retail barcode construct to aid in establishing uniqueness. … This six-digit field is used and encoded in Postal Service-created barcodes. The mailer shall use this field within the retail barcode construct to help maintain uniqueness and help with traceability to an exact printing source. … This field is used and encoded in Postal Service-created barcodes. The mailer shall use this field within the retail barcode construct to aid in establishing uniqueness. A 4-digit, YDDD format will be used. … This shall include identifying instances where no extra services have been purchased, e.g., Parcel Post with no extra services. … The service type code also identifies if the mailpiece belongs to a special Postal Service program, such as Open & Distribute or Merchandise Return Service.”

[^49]: [Intelligent Mail® Package Barcode (IMpb) Specification](https://postalpro.usps.com/mnt/glusterfs/2018-02/BarcodePackageIMSpec.pdf#page=12), page 7: “A Package Identification Code or PIC is a unique data string that serves as a unique tracking number for a mailpiece. Each PIC will consist of an Application Identifier, service type code, data string that will vary based upon the specific data construct, and a MOD 10 check digit.”

[^50]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=38), page 38: “In addition to the IMpb itself, the Intelligent Mail package barcode segment of the label also includes a human readable representation of the Package Identification Code, a USPS banner, and identification bars.”

[^51]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=15), page 15: “This segment may be also used for specific shipment or shipper information including branding and logos.”

[^52]: [USPS Ship Frequently Asked Questions](https://postalpro.usps.com/mnt/glusterfs/2026-01/20260106_USPS_Ship_FAQs_0.pdf#page=1), page 1: “The parcel labeling guide has been updated with information regarding USPS Ship label requirements.”

[^53]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=25), page 25: “4.4. USPS Ship Retail Entry Labels Additional label markings are required when using USPS Ship Retail Entry.”

[^54]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=49), page 49: “10. Appendix F: Sample Labels Figure 29: USPS Ground Advantage USPS Ship Figure 30: Priority Mail Express USPS Ship”

[^55]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=40), page 40: “The overall minimum height of the IMpb must measure at least 3/4 inch. … The Intelligent Mail package barcode requires an X-dimension measuring between 0.013 inch (13.0 mils) and 0.021 inch (21.0 mils). … A GS1-128 barcode’s X-dimension is the nominal width of the narrowest bar or space element within the barcode. … A clear zone measuring at least ten times the X-dimension must be maintained immediately to the left and right of the IMpb. … USPS recommends a printer with a minimum resolution of 203 dots per inch (dpi) for printing the Intelligent Mail package barcode.”

[^56]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=17), page 17: “In this case, a 0.5-inch service icon in parallel with the service banner is recommended as shown in Figure 11 below.”

[^57]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=42), page 42: “No barcode banner, human readable representation or identification bars are required. … An IMmb is optional but recommended in the Additional Information and User segment. … On smaller labels, such as the 6x3 label, the IMmb in the address location may need to be relocated to left of the return address.”

[^58]: [IMpb/IMmb Electronic File Transmission Requirements](https://postalpro.usps.com/mnt/glusterfs/2026-07/7.27.26%20Fact%20Sheet%20IMpb-IMmb%20and%20Electronic%20File%20Transmission%20Requirements.pdf#page=1), PDF page 1: “All classes of parcel mail (with the exception of BPM NonPresorted) are required to apply IMpb & IMmb barcodes as defined in DMM 204.2.1.1. … An IMmb is a supplemental GS1-DataMatrix (2D) barcode, which is intended to improve package visibility. The IMmb contains the same data as the IMpb barcode, using a space-efficient barcode symbology”

[^59]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=20), page 21: “Barcodes are validated for readability as well as their proper construction in the SSF. … Package labels are validated for proper content and use. … Barcode data and package label contents that fail validation will be assigned a non-compliance code of “BQ” (Barcode Quality). … 120 Days Uniqueness, occurs when PTR receives a mailpiece with the same tracking number, with a different EFN, Destination ZIP Code, or weight within 120 days of receiving the tracking number … Valid and Certified Mailer ID in the label that’s in Program Registration/Online Enrollment … Verify that the service type code in the barcode is a valid, active service type code … GRND ADVTG STC NO MATCHING SERVICE ICON BQ Verify the label has the correct service icon for the service type code … GRND ADVTG SERVICE BANNER NO MATCHING STC BQ Verify the label has the correct service banner for the service type code … GRND ADVTG INDICIA NO MATCHING STC BQ Verify the label has the correct indicia for the service type code … Verify that the mailer provided weight of the item being shipped falls within the range of weights for the service type code.”

[^60]: [IMpb (Intelligent Mail® Package Barcode & IMmb (Intelligent Mail® Matrix Barcode) Verification Fact Sheet](https://postalpro.usps.com/mnt/glusterfs/2026-05/IMpb%20Fact%20Sheet%2020251003%20V37.pdf#page=1), PDF page 1: “Mailers are assessed IMpb/IMmb non-compliance fees for competitive products when non-compliant pieces exceed the threshold for one of these three requirement categories: Barcode Quality, Manifest Quality, and Address Quality. … Submitting parcels without the necessary barcodes and electronic documentation may lead to mail rejection or parcel interception.”

[^61]: [Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systems](https://postalpro.usps.com/mnt/glusterfs/2026-07/Pub%20199_v35_07022026.pdf#page=62), page 63: “Package Quality Noncompliance assessments for Hazardous Materials (HAZMAT) packages with missing or mismatched IMmb will begin January 19, 2025. … Package Quality Noncompliance assessments for non-HAZMAT packages with missing or mismatched IMmb will begin April 1, 2025.”

[^62]: [Parcel Labeling Guide](https://postalpro.usps.com/mnt/glusterfs/2024-12/Parcel%20Labeling%20Guide%203.5.pdf#page=48), page 48: “Improperly applied shipping labels can cause scanning problems and affect the quality of tracking data provided by USPS. … Always place the label fully on the address side of the package without overlapping the side or any other label. … Do not cover USPS barcodes with tape or plastic wrap that may negatively impact readability of these barcodes.”

---

Unofficial. Not affiliated with or endorsed by the United States Postal Service. This is https://postalref.com/guides/package-labels as Markdown.