Intelligent Mail Barcode
The Intelligent Mail barcode is a 65-bar USPS barcode used to sort and track letters and flats.PostalPro: Intelligent Mail® Barcode“The Intelligent Mail barcode is a 65-bar Postal Service™ barcode used to sort and track letters and flats.”USPS original One barcode can carry requests for many services at once.PostalPro: Intelligent Mail® Barcode“offers greater versatility by allowing many services to be requested and embedded within one barcode”USPS original Mailers must print it on letters and flats prepared for automation prices.PostalPro: Intelligent Mail® Barcode“The IMb is required for use on letters and flats prepared for automation prices.”USPS original
What it is
The Intelligent Mail barcode is a height-modulated barcode.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 1“The IMb is a height-modulated barcode that encodes up to 31 digits of mailpiece data into 65 vertical bars”USPS original It encodes up to 31 digits of mailpiece data into 65 vertical bars.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 1“The IMb is a height-modulated barcode that encodes up to 31 digits of mailpiece data into 65 vertical bars”USPS original Each bar is one of four types: full, tracker, ascender or descender.Intelligent Mail® Barcode FAQPDF page 1“vertical bar types (Full, Tracker, Ascender and Descender)”USPS original It is also known as the USPS 4-State Customer Barcode.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 1“USPS 4-State Customer Barcode”USPS original
The barcode replaced two older barcodes.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 18“The IMb has replaced the use of the PLANET Code. … The IMb has replaced the use of the POSTNET barcode.”USPS original It combines the data of the POSTNET and PLANET Code barcodes, plus other data, into one barcode.PostalPro: Intelligent Mail® Barcode“The Intelligent Mail barcode combines the data of the existing POSTNET™ and the PLANET Code® barcodes, as well as other data, into a single barcode.”USPS original The POSTNET barcode stayed acceptable for automation prices only until May 2011.Intelligent Mail® Barcode Technical Resource Guidepage 11“note that the POSTNET barcode is acceptable for automaton prices only until May 2011.”USPS original
Mailers can use the barcode on automation-rate First-Class Mail, Standard Mail, Periodicals and Bound Printed Matter letters and flats.Intelligent Mail® Barcode Technical Resource Guidepage 7“The Postal Service allows mailers to use the Intelligent Mail barcode on automation-rate First-Class Mail®, Standard Mail®, Periodicals, and Bound Printed Matter letters and flats for rate eligibility in lieu of the POSTNET barcode.”USPS original Mailers apply most of these barcodes.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 1“Mailers primarily apply the IMb.”USPS original USPS also defines formats of the barcode that only USPS prints.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 1“the Postal Service has now defined formats of the IMb”USPS original
Mailers use the barcode in one of three ways: non-automation, basic automation or Full-Service.PostalPro: Intelligent Mail® Barcode“There are three options for using the IMb: non-automation, basic automation, and Full-Service.”USPS original Business Mail Entry Units began accepting letters with the barcode in September 2006.Intelligent Mail® Barcode FAQPDF page 1“started accepting letters with Intelligent Mail barcode in September of 2006”USPS original In May 2007, USPS allowed it on automation-rate flats.Intelligent Mail® Barcode FAQPDF page 1“In May of 2007 the Postal Service expanded use of the Intelligent Mail barcode by allowing mailers to use it on automation-rate flat-size mailpieces.”USPS original
The barcode also carries requests for OneCode ACS, a version of Address Change Service.Intelligent Mail® Barcode FAQPDF page 1“a version of Address Change Service™ (ACS™) called OneCode ACS™.”USPS original OneCode ACS gives mailers of letters and flats electronic or automated address corrections, and it is the foundation of Full-Service ACS.Service Type Identifier (STID) Quick Service GuidePDF page 1“The foundation for today’s Full Service ACS, OneCode ACS allows customers mailing letters or flats to receive electronic or automated address corrections.”USPS original It needs a Basic barcode whose Service Type Identifier requests an address correction service.Service Type Identifier (STID) Quick Service GuidePDF page 1“OneCode ACS requires a Basic Intelligent Mail barcode that contains a Basic/Nonauto STID requesting one of several ancillary services and options.”USPS original
A look-alike exists. The Flat Mail Identification Code Sort program uses another 4-state barcode as an ID tag on non-barcoded flats only.Intelligent Mail® Barcode FAQPDF page 1“uses another type of 4-state barcode that looks similar to the Intelligent Mail barcode, but it is applied as an ID tag on non-barcoded flat mail pieces only”USPS original
How it works
A mailer turns five data fields into one digit string, then into bars.Steps to Create the Intelligent Mail® BarcodePDF page 1“The five IMb fields are the Barcode Identifier, the Service Type Identifier, the Mailer ID,”USPS original An encoder converts the digits into a 65-character string.Steps to Create the Intelligent Mail® BarcodePDF page 1“An encoder is required to convert the digits into a 65-character string”USPS original A special font turns that string into the printed bars.Steps to Create the Intelligent Mail® BarcodePDF page 1“required to convert the 65-character string into the IMb”USPS original
The path from data to a printed barcode.
- Download and install the barcode encoder and font.Steps to Create the Intelligent Mail® BarcodePDF page 1“STEP 1: Download and Install the Encoder and Font”USPS original
- Apply for a Mailer ID, which every barcode needs.Steps to Create the Intelligent Mail® BarcodePDF page 1“A Mailer Identifier (Mailer ID or MID) is required for the IMb.”USPS original
- Fill in the five fields of the barcode.Steps to Create the Intelligent Mail® BarcodePDF page 1“The five IMb fields are the Barcode Identifier, the Service Type Identifier, the Mailer ID,”USPS original
- Join the five fields into a string of 20 to 31 digits.Steps to Create the Intelligent Mail® BarcodePDF page 2“they are ready to put the five fields together to form the 20- to 31-digit”USPS original
- Encode the string to 65 characters and print it with the barcode font.Steps to Create the Intelligent Mail® BarcodePDF page 2“string, encode it to 65 characters, and convert the 65-character string using the IMb font to”USPS original
- Print samples to check the print quality.Steps to Create the Intelligent Mail® BarcodePDF page 1“verify the print quality by producing samples,”USPS original
The barcode always has 65 bars, whatever the length of the ZIP Code in it.Intelligent Mail® Barcode Technical Resource Guidepage 9“the Intelligent Mail barcode is always 65 bars regardless of ZIP”USPS original The data fields carry no checksum.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 3“NOTE: No error detection and correction, such as a checksum, shall be included as part of the data fields; error detection and correction shall be added as part of the encoding process.”USPS original The encoding process adds error detection and correction.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 3“NOTE: No error detection and correction, such as a checksum, shall be included as part of the data fields; error detection and correction shall be added as part of the encoding process.”USPS original
The five fields
The barcode holds a 20-digit tracking code and a routing code of up to 11 digits.Steps to Create the Intelligent Mail® BarcodePDF page 1“The Intelligent Mail barcode consists of a 20-digit Tracking Code (Barcode Identifier, Service Type Identifier, Mailer Identifier, and Serial Number) and a Routing Code (ZIP Code™) field of up to 11 digits.”USPS original The tracking code has four fields and the routing code is the fifth.Steps to Create the Intelligent Mail® BarcodePDF page 1“The Intelligent Mail barcode consists of a 20-digit Tracking Code (Barcode Identifier, Service Type Identifier, Mailer Identifier, and Serial Number) and a Routing Code (ZIP Code™) field of up to 11 digits.”USPS original
| Field | Digits | What it holds |
|---|---|---|
| Barcode Identifier | 2 | The presort level printed on the optional endorsement lineIntelligent Mail® Barcode FAQPDF page 3“A 2-digit field reserved to encode the presort identification printed in human-readable form on the Optional Endorsement Line (OEL).”USPS original |
| Service Type Identifier | 3 | The class of mail and the services requestedIntelligent Mail® Barcode FAQPDF page 3“A 3-digit field used to identify the class of mail and any additional or special services requested for the piece. Defines the mailpiece as Full-Service, Basic or Non-Automation. Used to determine the disposition of Undeliverable-As-Addressed (UAA) mail.”USPS original |
| Mailer ID | 6 or 9 | The mail owner or mail preparerIntelligent Mail® Barcode FAQPDF page 3“A USPS-assigned 6 or 9-digit (depending on mail volume) field used to identify the mail owner or mail preparer.”USPS original |
| Serial Number | 9 or 6 | A number the mailer definesIntelligent Mail® Barcode FAQPDF page 3“A 6 or 9-digit field (depending on MID) defined by the mailer.”USPS original |
| Routing Code | 0, 5, 9 or 11 | The delivery ZIP Code in the addressIntelligent Mail® Barcode FAQPDF page 3“5-digit, 9-digit, or 11-digit field that identifies the delivery ZIP Code data in the address.”USPS original |
The Barcode Identifier is a 2-digit field for the presort identification on the optional endorsement line, a printed line that shows the sort level.Intelligent Mail® Barcode FAQPDF page 3“A 2-digit field reserved to encode the presort identification printed in human-readable form on the Optional Endorsement Line (OEL).”USPS original It is usually 00 when the mailpiece has no such line.Barcode IdentifierPDF page 1“Generally, this field should be left as “00” (zero-zero) if an OEL is not printed on the mailpiece.”USPS original Its second digit must be 0 to 4.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 3“the second digit shall be constrained to the range of 0–4.”USPS original
The Service Type Identifier marks the piece as Full-Service, Basic or Non-Automation.Intelligent Mail® Barcode FAQPDF page 3“A 3-digit field used to identify the class of mail and any additional or special services requested for the piece. Defines the mailpiece as Full-Service, Basic or Non-Automation. Used to determine the disposition of Undeliverable-As-Addressed (UAA) mail.”USPS original It also decides what happens to mail that is undeliverable as addressed.Intelligent Mail® Barcode FAQPDF page 3“A 3-digit field used to identify the class of mail and any additional or special services requested for the piece. Defines the mailpiece as Full-Service, Basic or Non-Automation. Used to determine the disposition of Undeliverable-As-Addressed (UAA) mail.”USPS original The class of mail, the address correction service and the tracking service decide which value a mailer uses.Steps to Create the Intelligent Mail® BarcodePDF page 1“The attributes that determine which Service Type Identifier (STID) should appear in an IMb are the class”USPS original USPS publishes a table that shows which value to use for each combination.Service Type Identifier (STID) Quick Service GuidePDF page 1“The STID Table located on the PostalPro® website allows you to determine which STID to use based on the mail class, address correction option”USPS original
Service Type Identifiers from the USPS STID table. Filter by class of mail, address correction group, service level or tracking option.
| STID | Mail class | Group | Option | Service level | Informed Visibility Mail Tracking & Reporting |
|---|---|---|---|---|---|
| 300 | First-Class Mail® | No Address Corrections – No Printed Endorsements | Basic or Nonautomation | Without IV® MTR | |
| 310 | First-Class Mail® | No Address Corrections – No Printed Endorsements | Basic or Nonautomation | With IV® MTR | |
| 260 | First-Class Mail® | No Address Corrections – No Printed Endorsements | Full-Service | Without IV® MTR | |
| 270 | First-Class Mail® | No Address Corrections – No Printed Endorsements | Full-Service | With IV® MTR | |
| 700 | First-Class Mail® | Manual Corrections ** | Basic or Nonautomation | Without IV® MTR | |
| 040 | First-Class Mail® | Manual Corrections ** | Basic or Nonautomation | With IV® MTR | |
| 230 | First-Class Mail® | OneCode ACS® | Address Service Requested Opt 1 | Basic or Nonautomation | Without IV® MTR |
| 220 | First-Class Mail® | OneCode ACS® | Address Service Requested Opt 1 | Basic or Nonautomation | With IV® MTR |
| 080 | First-Class Mail® | OneCode ACS® | Address Service Requested Opt 2 | Basic or Nonautomation | Without IV® MTR |
| 140 | First-Class Mail® | OneCode ACS® | Address Service Requested Opt 2 | Basic or Nonautomation | With IV® MTR |
| 504 | First-Class Mail® | OneCode ACS® | Change Service Requested Opt 1 ♻ | Basic or Nonautomation | Without IV® MTR |
| 502 | First-Class Mail® | OneCode ACS® | Change Service Requested Opt 1 ♻ | Basic or Nonautomation | With IV® MTR |
| 082 | First-Class Mail® | OneCode ACS® | Change Service Requested Opt 2 ♻ | Basic or Nonautomation | Without IV® MTR |
| 240 | First-Class Mail® | OneCode ACS® | Change Service Requested Opt 2 ♻ | Basic or Nonautomation | With IV® MTR |
| 341 | First-Class Mail® | OneCode ACS® | Return Service Requested Opt 2 | Basic or Nonautomation | Without IV® MTR |
| 340 | First-Class Mail® | OneCode ACS® | Return Service Requested Opt 2 | Basic or Nonautomation | With IV® MTR |
| 345 | First-Class Mail® | OneCode ACS® | Temp-Return Service Requested Opt 2 | Basic or Nonautomation | Without IV® MTR |
| 344 | First-Class Mail® | OneCode ACS® | Temp-Return Service Requested Opt 2 | Basic or Nonautomation | With IV® MTR |
| 320 | First-Class Mail® | Full-Service ACS™ | Address Service Requested Opt 1 | Full-Service | Without IV® MTR |
| 314 | First-Class Mail® | Full-Service ACS™ | Address Service Requested Opt 1 | Full-Service | With IV® MTR |
1 to 20 of 230 codes in the Service Type IDentifier (STID) Table, effective January 21, 2024.
The Mailer ID is a number USPS assigns to a mail owner or mail preparer.Intelligent Mail® Barcode FAQPDF page 3“A USPS-assigned 6 or 9-digit (depending on mail volume) field used to identify the mail owner or mail preparer.”USPS original Six-digit Mailer IDs begin with 0 through 8, and nine-digit ones begin with 9.Steps to Create the Intelligent Mail® BarcodePDF page 1“All Six-digit MIDs begin with ‘0’ through ‘8’; nine-digit MIDs begin with ‘9’.”USPS original
The Serial Number takes the digits the Mailer ID leaves: 9 digits with a 6-digit Mailer ID, 6 with a 9-digit one.Steps to Create the Intelligent Mail® BarcodePDF page 2“the MID, the Serial Number is either a nine- or six-digit number.”USPS original With the Mailer ID and class of mail, it can identify a single mailpiece.Steps to Create the Intelligent Mail® BarcodePDF page 2“The Serial Number, in conjunction with the MID and class of mail, can uniquely identify the mailpiece.”USPS original The Full-Service option requires that each mailpiece be uniquely identified.Steps to Create the Intelligent Mail® BarcodePDF page 2“Mail's Full-Service option does require that mailpieces be uniquely identified.”USPS original Basic automation prices do not require a unique Serial Number.Intelligent Mail® Barcode Technical Resource Guidepage 9“Serial Number uniqueness is not required when qualifying for basic automation prices.”USPS original
The Routing Code holds a 5-digit ZIP Code, a ZIP+4 code or an 11-digit delivery-point code.Steps to Create the Intelligent Mail® BarcodePDF page 2“The Routing Code can contain a 5-digit ZIP Code, Nine-digit ZIP+4 code, or 11-digit delivery-point code.”USPS original Automation discounts need a delivery-point ZIP Code from CASS-certified software.Steps to Create the Intelligent Mail® BarcodePDF page 2“To obtain automation discounts, a Delivery-Point ZIP Code from CASS-certified (Coding Accuracy”USPS original A mailer may leave the Routing Code empty and use the barcode only for tracking.Steps to Create the Intelligent Mail® BarcodePDF page 2“Mailers may opt not to populate the ZIP Code and use the IMb”USPS original
USPS gives an example of the whole string.Steps to Create the Intelligent Mail® BarcodePDF page 2“Digit String: 0027012345620080000198765432101”USPS original
| Field | Example value |
|---|---|
| Barcode Identifier | 00Steps to Create the Intelligent Mail® BarcodePDF page 2“Digit String: 0027012345620080000198765432101”USPS original |
| Service Type Identifier | 270Steps to Create the Intelligent Mail® BarcodePDF page 2“EXAMPLE: Service Type ID of 270 (First-Class Mail, Intelligent Mail Full-Service option, with Confirm service, no address correction), Mailer ID 123456, uniquely identified by Serial Number 200800001, going to ZIP Code 98765-4321(01), is encoded like this:”USPS original |
| Mailer ID | 123456Steps to Create the Intelligent Mail® BarcodePDF page 2“EXAMPLE: Service Type ID of 270 (First-Class Mail, Intelligent Mail Full-Service option, with Confirm service, no address correction), Mailer ID 123456, uniquely identified by Serial Number 200800001, going to ZIP Code 98765-4321(01), is encoded like this:”USPS original |
| Serial Number | 200800001Steps to Create the Intelligent Mail® BarcodePDF page 2“EXAMPLE: Service Type ID of 270 (First-Class Mail, Intelligent Mail Full-Service option, with Confirm service, no address correction), Mailer ID 123456, uniquely identified by Serial Number 200800001, going to ZIP Code 98765-4321(01), is encoded like this:”USPS original |
| Routing Code | 98765432101Steps to Create the Intelligent Mail® BarcodePDF page 2“EXAMPLE: Service Type ID of 270 (First-Class Mail, Intelligent Mail Full-Service option, with Confirm service, no address correction), Mailer ID 123456, uniquely identified by Serial Number 200800001, going to ZIP Code 98765-4321(01), is encoded like this: … Digit String: 0027012345620080000198765432101”USPS original |
| Full string | 0027012345620080000198765432101Steps to Create the Intelligent Mail® BarcodePDF page 2“Digit String: 0027012345620080000198765432101”USPS original |
The example's Service Type Identifier, as the STID table lists it.
Service Type IDentifier (STID) Table, effective January 21, 2024, 270Service Type Identifier (STID) Table Effective January 21, 2024Effective January 21, 2024 · PDF page 2STID270Mail classFirst-Class Mail®OptionNo Address Corrections – No Printed EndorsementsService levelFull-ServiceInformed Visibility Mail Tracking & ReportingWith IV® MTRUSPS original
- Mail class
- First-Class Mail®
- Group
- —
- Option
- No Address Corrections – No Printed Endorsements
- Service level
- Full-Service
- Informed Visibility Mail Tracking & Reporting
- With IV® MTR
Placement and size
On letters, the barcode goes in the address block or in the barcode clear zone.Intelligent Mail® Barcode FAQPDF page 2“On letters, it can be placed either in the address block or in the barcode clear zone”USPS original On flats, it can go anywhere on the address side at least 1/8 inch from any edge.Intelligent Mail® Barcode FAQPDF page 2“On flats, the Intelligent Mail barcode can be placed anywhere on the address side as long as it is at least 1/8th inch from any edge of the piece.”USPS original Only one Intelligent Mail barcode can go in the same area.Intelligent Mail® Barcode Technical Resource Guidepage 11“To avoid ambiguity, only one Intelligent Mail barcode can be placed in the same area.”USPS original
The print specification lets mailers choose the barcode's height and width within limits.Intelligent Mail® Barcode FAQPDF page 2“The print specification allows mailers some flexibility in choosing the”USPS original
| Measure | Limit |
|---|---|
| Overall height | 0.125 inch to 0.165 inchIntelligent Mail® Barcode FAQPDF page 2“Vertical dimensions shall be based on the centerline of the barcode, forming an overall barcode height of 0.125 inch to 0.165 inch.”USPS original |
| Pitch | 22 ±2 bars per inchIntelligent Mail® Barcode FAQPDF page 2“Horizontal dimensions shall be based on the centerline of the individual bars, forming an overall barcode pitch of 22 ±2 bars per inch.”USPS original |
| Clear zone | 0.028 inch above and below, 0.125 inch on each endIntelligent Mail® Barcode FAQPDF page 2“A minimum clear zone shall be 0.028 inch above and below the barcode and 0.125 inch on each end of the barcode.”USPS original |
Encoder software and fonts
USPS provides Intelligent Mail barcode files, fonts and encoders for download.PostalPro: Intelligent Mail Barcode (IMb) Encoder Software and Fonts“The Postal Service provides Intelligent Mail® barcode files, fonts and encoders, available for download.”USPS original They are for Full-Service mailers who print their own barcodes.PostalPro: Intelligent Mail Barcode (IMb) Encoder Software and Fonts“Full-Service Mailers printing their own Intelligent Mail barcodes.”USPS original USPS makes them available at no charge, with a web-based encoder-decoder tool.Intelligent Mail® Barcode Technical Resource Guidepage 10“To facilitate the adoption of the Intelligent Mail barcode, the Postal Service has developed, and is making available at no charge, a web-based, interactive encoder-decoder tool, and an extensive library of encoding software and fonts suitable for encoding and printing the Intelligent Mail barcode in mail production environments using selected operating systems and printing architectures.”USPS original The tool converts a barcode into its digits, or digits into a barcode.PostalPro: Intelligent Mail Barcode (IMb) Encoder Software and Fonts“The IMb encoder and decoder tool allows you to convert Intelligent Mail® barcodes into numeric equivalents, or vice versa.”USPS original
Specification USPS-B-3200 defines the algorithm that turns the 31 digits into 65 bars.Intelligent Mail® Barcode Technical Resource Guidepage 10“The encoding algorithm that translates the 31 digits in the payload into 65 bars is defined in the USPS publication, Specification USPS-B-3200, which is available for download from PostalPro.”USPS original The encoder takes two inputs: a 20-digit tracking code and a routing code of none, 5, 9 or 11 digits.Intelligent Mail® Barcode Technical Resource Guidepage 10“Each call to the encoder requires two arguments: a 20-digit tracking code, and none, 5, 9, or 11-digit routing code.”USPS original It returns a status and a 65-character string of the letters F, A, D and T, for a full bar, ascender, descender or tracker.Intelligent Mail® Barcode Technical Resource Guidepage 10“The encoder will return the status of the encoding function along with a 65-character string of the letters F, A, D, or T, representing a full bar, ascender, descender, or tracker, respectively.”USPS original The font turns that string into the printed bars.Intelligent Mail® Barcode Technical Resource Guidepage 5“Apply font to 65-character string (fonts available on PostalPro).”USPS original
The encoder comes as one package for each operating system, a standard ZIP file.Intelligent Mail® Barcode Technical Resource Guidepage 10“For each operating system, the encoding software package is distributed as a standard ZIP file.”USPS original Each package holds a user guide on installing and using its files.Intelligent Mail® Barcode Technical Resource Guidepage 10“A user guide is included in each package to provide detailed operating system and language-specific instructions on how to install and use the files in the package.”USPS original
| Part | What USPS supports |
|---|---|
| Encoder languages | C, Java 2, COBOL and PL/1PostalPro: Intelligent Mail Barcode (IMb) Encoder Software and Fonts“The Postal Service provides software support for 24 combinations of language environments (C, Java 2, COBOL, and PL/1) on 9 unique platforms (z/OS, VSE/ESA, OS/400, AIX, Linux, Solaris, HP/UX, Mac, and Windows).”USPS original |
| Platforms | z/OS, VSE/ESA, OS/400, AIX, Linux, Solaris, HP/UX, Mac and WindowsPostalPro: Intelligent Mail Barcode (IMb) Encoder Software and Fonts“The Postal Service provides software support for 24 combinations of language environments (C, Java 2, COBOL, and PL/1) on 9 unique platforms (z/OS, VSE/ESA, OS/400, AIX, Linux, Solaris, HP/UX, Mac, and Windows).”USPS original |
| Font printing environments | AFP, HP PCL, PostScript, Xerox Metacode and TrueTypePostalPro: Intelligent Mail Barcode (IMb) Encoder Software and Fonts“For printing Intelligent Mail® barcodes in a production environment, a variety of Intelligent Mail barcode fonts are available for 5 major production printing environments: AFP (MVS, AS/400, VM, VSE), HP PCL, PostScript, Xerox Metacode, and TrueType.”USPS original |
USPS licenses the software, documentation and fonts for use in the mailing industry without a royalty or other fee.PostalPro: Intelligent Mail Barcode (IMb) Encoder Software and Fonts“a world-wide, revocable, license to use them in the mailing industry without paying the Postal Service a royalty or other fee”USPS original The license lasts while the user holds a copy, or for the life of the longest copyright if that is shorter.PostalPro: Intelligent Mail Barcode (IMb) Encoder Software and Fonts“It remains effective so long as you have a copy of the Software, Documentation, and/or Fonts or, if shorter, for the life of the longest Copyright in the Software, Documentation, and/or Fonts.”USPS original USPS may change the license within reason at its discretion.PostalPro: Intelligent Mail Barcode (IMb) Encoder Software and Fonts“The US Postal Service reserves the right to change this License in any manner within reason at its discretion.”USPS original
Redistribution of the Software, Documentation, and/or Font must contain (a) the copyright notice set forth below, (b) this list of conditions, and (c) the disclaimer noted below.PostalPro: Intelligent Mail Barcode (IMb) Encoder Software and Fonts“Redistribution of the Software, Documentation, and/or Font must contain (a) the copyright notice set forth below, (b) this list of conditions, and (c) the disclaimer noted below.”USPS original
Anyone who passes the software, documentation or fonts on to others must include the copyright notice, the license's conditions and its disclaimer.
Intelligent Mail for Small Business Mailers
Intelligent Mail for Small Business Mailers is a free online tool that produces presorted Intelligent Mail barcodes for mailpieces and tray labels.PostalPro: Intelligent Mail® for Small Business Mailers (IMsb)“Intelligent Mail® for Small Business Mailers (IMsb) is a free online tool which will allow you to produce the presorted Intelligent Mail barcodes (IMb) for your mail pieces, tray labels and submit an electronic postage statement to the acceptance units.”USPS original It also submits an electronic postage statement to the acceptance unit.PostalPro: Intelligent Mail® for Small Business Mailers (IMsb)“Intelligent Mail® for Small Business Mailers (IMsb) is a free online tool which will allow you to produce the presorted Intelligent Mail barcodes (IMb) for your mail pieces, tray labels and submit an electronic postage statement to the acceptance units.”USPS original It is a Full-Service mailing solution for small business mailers who prepare their own mailings.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“The Intelligent Mail for Small Business (IMsb) tool is a Full-Service mailing solution specifically designed for small business mailers who wish to prepare their own mailings.”USPS original
The tool is for First-Class Mail and USPS Marketing Mail permit holders mailing cards, letters and flats.PostalPro: Intelligent Mail® for Small Business Mailers (IMsb)“First-Class Mail and USPS Marketing Mail permit holders mailing cards, letters and flats.”USPS original It qualifies mailings of fewer than 50,000 pieces entered at a Business Mail Entry Unit for automation Full-Service discounts.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“This tool allows small business mailers to qualify for automation Full-Service discounts on mailings that are: … Maximum mailing size of fewer than 50,000 pieces for mail entered at a BMEU.”USPS original It is not designed for Mail Service Providers who prepare mail for others.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“The IMsb Tool is not designed for use by Mail Service Providers who prepare mail on behalf of others.”USPS original
A mailer needs three things first: a postage permit, a registration on the Business Customer Gateway with a linked permit, and an address list.PostalPro: Intelligent Mail® for Small Business Mailers (IMsb)“Mailing Permit: Mailers must have a postage permit, which can be obtained by visiting your local BMEU … Registration: Mailers must be registered on Business Customer Gateway and have a linked postage permit.”USPS original The list is a Microsoft Excel or CSV file.PostalPro: Intelligent Mail® for Small Business Mailers (IMsb)“Have a Database/Address list in one of the following formats: Microsoft Excel 2010, Microsoft Excel 2007, Microsoft Excel 2003, Comma Separated Value (CSV).”USPS original The tool runs in a web browser, with no special software to install.PostalPro: Intelligent Mail® for Small Business Mailers (IMsb)“To use the IMsb, no special software or installation is required. Users simply access the application via a web browser.”USPS original
How a mailer prepares a mailing with the tool.
- Open the tool from the Mailing Services menu in the Business Customer Gateway.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“Access the IMsb Tool from the Mailing Services menu in the BCG”USPS original
- Set up the mailing and upload the address list.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“Set up the mailing and upload the address list. (Excel or CSV file)”USPS original
- The tool confirms that the addresses are valid delivery points.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“The IMsb Tool will confirm that the addresses on the list are valid delivery points.”USPS original
- The tool presorts the mailing for the presort discounts the list qualifies for.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“The IMsb Tool will automatically presort the mailing according to the address list, providing full presort discounts such as 5-digit/3-digit/Mixed automation pricing, SCF and None entry discounts if applicable.”USPS original
- Print addresses with unique barcodes on labels, envelopes or insert pages, with barcoded tray labels.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“Print addresses with a unique Intelligent Mail barcode on labels, envelopes, or insert pages, along with unique barcoded letter and flat tray labels.”USPS original
- Submit the postage statement electronically.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“Submit the postage statement electronically.”USPS original
The tool is built to meet Full-Service requirements.PostalPro: Intelligent Mail® for Small Business Mailers (IMsb)“The IMsb Tool has been specifically developed for small business mailers to meet Full-Service requirements.”USPS original It puts a unique Intelligent Mail barcode in the address block.PostalPro: Intelligent Mail® for Small Business Mailers (IMsb)“The IMsb Tool generates a unique Intelligent Mail barcode within the address block.”USPS original To use Mail Merge with the tool, a mailer needs the barcode font.PostalPro: Intelligent Mail® for Small Business Mailers (IMsb)“Instructions for obtaining the IMb font required in order to be able to use Mail Merge with the IMsb Tool.”USPS original The tool cleanses the address list and can find duplicate addresses, but this is not a Move Update method.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“IMsb cleanses the address list ensuring all addresses are valid and can identify duplicate addresses. (This is not a Move Update method)”USPS original
Full-Service mailings from the tool get the $0.003 per piece Full-Service discount.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“Receive the $0.003 per piece Full-Service Discount”USPS original Address Change Service is available on Full-Service pieces.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“Address Correction Service (ACS) available on Full-Service pieces”USPS original Users of the tool may qualify for the Seamless Acceptance program.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“IMsb Tool users may qualify for the Seamless Acceptance program.”USPS original
User Guides
- Intelligent Mail Small Business (IMsb) Tool User GuideAugust 25, 2026
Fact Sheets
- Intelligent Mail® for Small Business (IMsb) Fact SheetOctober 22, 2026
Rules
The Intelligent Mail barcode must contain a proper routing ZIP Code™ and a valid Mailer ID (MID) to satisfy the criteria for automation prices.Intelligent Mail® Barcode FAQPDF page 1“The Intelligent Mail barcode must contain a proper routing ZIP Code™ and a valid Mailer ID (MID) to satisfy the criteria for automation prices.”USPS original
A barcode on mail claiming automation prices must hold a correct routing ZIP Code and a valid Mailer ID. Without both, the piece does not meet the criteria for those prices.
Mailers printing the Intelligent Mail barcode solely to qualify for automation prices must populate the Service Type ID field with one of the following values: 700 for First-Class Mail, 702 for Standard Mail, 704 for Periodicals, or 706 for Bound Printed Matter.Intelligent Mail® Barcode FAQPDF page 1“Mailers printing the Intelligent Mail barcode solely to qualify for automation prices must populate the Service Type ID field with one of the following values: 700 for First-Class Mail, 702 for Standard Mail, 704 for Periodicals, or 706 for Bound Printed Matter.”USPS original
A mailer who uses the barcode only for automation prices must put the Service Type Identifier for its class of mail in the barcode. The value depends on the class.
When mailers prepare flat-size pieces using IMbs to meet automation-price eligibility requirements, the IMbs on any pieces bearing printed OELs must contain the barcode identifier corresponding to the printed OEL used.Steps to Create the Intelligent Mail® BarcodePDF page 1“When mailers prepare flat-size pieces using IMbs to meet automation-price eligibility requirements, the IMbs on any pieces bearing printed OELs must contain the barcode identifier corresponding to the printed OEL used.”USPS original
On automation flats with a printed optional endorsement line, the Barcode Identifier must match that printed line.
The Routing Code, if populated, must never be padded with zeros, spaces or nulls that are not part of the valid ZIP Code.Intelligent Mail® Barcode Technical Resource Guidepage 9“The Routing Code, if populated, must never be padded with zeros, spaces or nulls that are not part of the valid ZIP Code.”USPS original
A Routing Code that is filled in must hold only the ZIP Code's own digits. A mailer must never add zeros, spaces or nulls to it.
For each of the required fields in the Tracking Code, the mailer shall add leading or trailing zeroes to achieve the correct field length.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 3“For each of the required fields in the Tracking Code, the mailer shall add leading or trailing zeroes to achieve the correct field length.”USPS original
Each required tracking code field must reach its full length. The mailer must add leading or trailing zeros to get there.
Mailers as well as the Postal Service shall perform routine physical inspection and testing of Intelligent Mail barcodes to ensure the quality of labels produced.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 17“Mailers as well as the Postal Service shall perform routine physical inspection and testing of Intelligent Mail barcodes to ensure the quality of labels produced.”USPS original
Both mailers and USPS must inspect and test printed barcodes as a routine. The goal is labels of the required quality.
What goes wrong
Registered Mail cannot get automation prices because of the way USPS handles it.PostalPro: Intelligent Mail® Barcode“Registered Mail is ineligible for automation prices because of the way it is handled during processing.”USPS original Business Reply Mail cannot use an 11-digit delivery-point code in the Routing Code.Intelligent Mail® Barcode Technical Resource Guidepage 9“Note that 11-digit delivery point codes are not permitted on Business Reply Mail (BRM).”USPS original
A Periodicals publisher can receive PS Form 3579 manual address correction notices.Service Type Identifier (STID) Table Effective January 21, 2024Effective January 21, 2024 · PDF page 3“PS Form 3579 manual address correction notices are generated under the following conditions:”USPS original This happens when no barcode is present or readable and the publication has no history of a Full-Service ACS value in the barcode.Service Type Identifier (STID) Table Effective January 21, 2024Effective January 21, 2024 · PDF page 3“No Intelligent Mail barcode is present or readable and there is no history of a Full-Service ACS STID in an IMb for that publication.”USPS original Using some Service Type Identifiers wrongly can cause unexpected costs to the mailer.Service Type Identifier (STID) Table Effective January 21, 2024Effective January 21, 2024 · PDF page 3“Improper use of this Service Type ID can create an unexpected and extraneous cost to the mailer.”USPS original
Terms
- Intelligent Mail BarcodeIMb, 4CB, Intelligent Mail barcode (piece level barcode), 4CB, 4-CB, USPS4CB, USPS 4-State Customer Barcode, 4-state customer barcode
- The IMb is a height-modulated barcode that encodes up to 31 digits of mailpiece data into 65 vertical bars using a 4-state symbology.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 1“The IMb is a height-modulated barcode that encodes up to 31 digits of mailpiece data into 65 vertical bars using a 4-state symbology.”USPS original
- Intelligent MailIM
- A Postal Service initiative for improving both mailpiece visibility and acceptance/delivery processes on letters, flats, packages, and mail aggregates.Intelligent Mail® Package Barcode (IMpb) Specificationpage 7“A Postal Service initiative for improving both mailpiece visibility and acceptance/delivery processes on letters, flats, packages, and mail aggregates.”USPS original
- Service Type IdentifiersSTID, STIDS, STI, Service Type IDs, Service Type ID(s)
- A unique three-digit code embedded in the Intelligent Mail® barcode (IMb®) that indicates the service type for an individual mailpiece.Ballot Mail & Political Mail STIDs Fact SheetPDF page 1“A unique three-digit code embedded in the Intelligent Mail® barcode (IMb®) that indicates the service type for an individual mailpiece.”USPS original
- 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.Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systemspage 474“MID is a unique 6- or 9-digit number that identifies the mailer or the mailer’s client.”USPS original
- IMb TracingConfirm, Intelligent Mail barcode (IMb) Tracing (formerly CONFIRM), OneCode Confirm
- IMb Tracing is a service that provides real-time tracking information for automation-compatible letters and flats, giving advance notice for both incoming and outgoing mail.Intelligent Mail® Barcode (IMb) 4-State Specificationpage 18“IMb Tracing is a service that provides real-time tracking information for automation-compatible letters and flats, giving advance notice for both incoming and outgoing mail.”USPS original
- OneCode ACSOCD, OneCode ACS feature
- The foundation for today’s Full Service ACS, OneCode ACS allows customers mailing letters or flats to receive electronic or automated address corrections.Service Type Identifier (STID) Quick Service GuidePDF page 1“The foundation for today’s Full Service ACS, OneCode ACS allows customers mailing letters or flats to receive electronic or automated address corrections.”USPS original
- Full-Service Intelligent MailFS, Full-Service, Full-Service Intelligent Mail option
- One of two Intelligent Mail offerings that requires a maximum 31-digit Intelligent Mail barcode comprising five fields: the Barcode ID, Service Type Identifier, Mailer ID, Serial Number, and Routing Code. The Full-Service Intelligent Mail option requires unique mailpiece barcodes, the use of Intelligent Mail barcodes on tray labels or container placards, electronic documentation, and the use of Facility Access and Shipment Tracking to schedule appointments for the entry of mailings.Publication 32: Glossary of Postal TermsPDF page 96“One of two Intelligent Mail offerings that requires a maximum 31-digit Intelligent Mail barcode comprising five fields: the Barcode ID, Service Type Identifier, Mailer ID, Serial Number, and Routing Code. The Full-Service Intelligent Mail option requires unique mailpiece barcodes, the use of Intelligent Mail barcodes on tray labels or container placards, electronic documentation, and the use of Facility Access and Shipment Tracking to schedule appointments for the entry of mailings.”USPS original
- Intelligent Mail Package BarcodeIMpb
- An IMpb is the USPS-developed barcode that can be read by automated parcel-processing equipment and scanning devices and consists of a data string that generally follows the GS1-128 specification.IMpb/IMmb Electronic File Transmission RequirementsPDF page 1“An IMpb is the USPS-developed barcode that can be read by automated parcel-processing equipment and scanning devices and consists of a data string that generally follows the GS1-128 specification.”USPS original
- Intelligent Mail Barcode (IMb) Encoder Software and Fonts
- The Postal Service provides Intelligent Mail® barcode files, fonts and encoders, available for download.PostalPro: Intelligent Mail Barcode (IMb) Encoder Software and Fonts“The Postal Service provides Intelligent Mail® barcode files, fonts and encoders, available for download.”USPS original
- Intelligent Mail for Small Business MailersIMsb, Intelligent Mail Small Business Tool, Intelligent Mail for Small Business, IMsb for Small Business Mailers, Intelligent Mail Small Business, IMsb Tool
- is a Full-Service mailing solution specifically designed for small business mailers who wish to prepare their own mailings.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“is a Full-Service mailing solution specifically designed for small business mailers who wish to prepare their own mailings.”USPS original
Documents
Tech Guides
- Intelligent Mail® Barcode (IMb) 4-State SpecificationApril 20, 2015
Publications
- Appendix B: ACS™ Frequently Asked QuestionsApril 15, 2026
User Guides
- Program Registration Online Enrollment User GuideJanuary 5, 2017
- Intelligent Mail® Barcode Technical Resource GuideJanuary 1, 2009
Quick Service Guides
Fact Sheets
- Service Type Identifier (STID) Table Effective January 21, 2024April 18, 2024
- Barcode IdentifierJanuary 3, 2013
- Intelligent Mail® Barcode ResourcesFebruary 4, 2008
FAQs
- Intelligent Mail® Barcode FAQMay 3, 2022
- Share Mail™ FAQSeptember 13, 2019
Contacts
For questions about the barcode, USPS lists the phone number 1-877-640-0724 and the email onecodesolution@usps.gov.PostalPro: Intelligent Mail® Barcode“For questions, please call 1-877-640-0724 or email onecodesolution@usps.gov.”USPS original Mailers without a Mailer ID can contact a Mailpiece Design Analyst at 1-877-672-0007 or MDA@usps.gov.Intelligent Mail® Barcode FAQPDF page 1“1-877-672-0007 or MDA@usps.gov”USPS original Questions about the Barcode Identifier go to IntelligentMailSupport@usps.gov.Barcode IdentifierPDF page 1“If you have any questions then you can send your enquiries to IntelligentMailSupport@usps.gov”USPS original The ACS Department answers questions about how to use Service Type Identifiers, at ACS@usps.gov or 877-640-0724.Service Type Identifier (STID) Table Effective January 21, 2024Effective January 21, 2024 · PDF page 3“ACS Department at ACS@usps.gov or (877-640-0724) for information on how these STIDs should be used.”USPS original For help with the Intelligent Mail for Small Business Mailers tool, the Mailing and Shipping Solutions Center answers at MSSC@usps.gov or (877) 672-0007.Intelligent Mail® for Small Business (IMsb) Fact SheetPDF page 1“For assistance, contact the Mailing and Shipping Solutions Center Email: MSSC@usps.gov Call: (877) 672-0007”USPS original
Sources
- PostalPro: Intelligent Mail® BarcodeUSPS original
- Intelligent Mail® Barcode (IMb) 4-State SpecificationUSPS original
- Intelligent Mail® Barcode FAQUSPS original
- Intelligent Mail® Barcode Technical Resource GuideUSPS original
- Service Type Identifier (STID) Quick Service GuideUSPS original
- Steps to Create the Intelligent Mail® BarcodeUSPS original
- Barcode IdentifierUSPS original
- Service Type Identifier (STID) Table Effective January 21, 2024, Effective January 21, 2024USPS original
- PostalPro: Intelligent Mail Barcode (IMb) Encoder Software and FontsUSPS original
- PostalPro: Intelligent Mail® for Small Business Mailers (IMsb)USPS original
- Intelligent Mail® for Small Business (IMsb) Fact SheetUSPS original
- Intelligent Mail® Package Barcode (IMpb) SpecificationUSPS original
- Ballot Mail & Political Mail STIDs Fact SheetUSPS original
- Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment SystemsUSPS original
- Publication 32: Glossary of Postal TermsUSPS original
- IMpb/IMmb Electronic File Transmission RequirementsUSPS original