USPS

About USPS service methods

Shipium supports use of USPS service methods via USPS (Direct), EasyPost, Endicia, and Pitney Bowes. This document includes guidance for configuring your account to use USPS Direct service methods and for special use cases such as passing particular packaging types to the carrier in your calls to our APIs.

USPS Direct

Account requirements

To start using USPS Direct service methods within the Shipium platform, you'll need to ensure your account is authorized to interact with USPS's APIs.

A USPS business account is required to use the USPS Direct service methods. You'll need to provide your:

You also can create a business account and generate a Mailer ID for label generation via the USPS Customer Onboarding Portal: https://cop.usps.com.

If you already have a USPS business account, you should reach out to your USPS account representative for USPS API onboarding support.

USPS Direct's service methods and their identifiers are listed on the Supported Carriers page.

Configure USPS Direct for your account

To set up a carrier contract for USPS Direct, you'll need to access the Shipium Console and follow instructions for adding a carrier contract to a fulfillment context. If your organization doesn't use fulfillment contexts for configuration, you can use the fulfillment configuration workflow.

For either approach, once you reach the step to edit or add a carrier account for USPS Direct, you'll be asked to enter credentials required by USPS, in addition to the fields Shipium requires. All fields are required unless noted as optional.

Shipping options with USPS Direct

Packaging types

Priority Mail Flat Rate®

USPS Priority Mail Flat Rate is a flat-rate shipping option that lets your organization ship packages that weigh 70 pounds or less to anywhere in the U.S. for a fixed price. You can find more details about this shipping method in USPS's Priority Mail documentation. Shipium supports selection of the Priority Mail Flat Rate shipping method.

To use the USPS Priority Mail Flat Rate shipping method, you'll first need to set up a carrier contract for the USPS Priority Mail Flat Rate in the Shipium Console.

Configure USPS Priority Mail Flat Rate for your account

To start using USPS Priority Mail Flat Rate within the Shipium platform, you'll need to set up your account in the Shipium Console to include the USPS Priority Mail Flat Rate service method. You can find instructions for establishing a fulfillment context for your organization and attaching a carrier service method and rate to that context in the Fulfillment Contexts documentation.

Specifically, once you have configured a fulfillment context with an origin (or fulfillment center), you'll follow the guidance in the Carrier Contracts documentation to establish carrier contracts, accounts, and rates. The carrier rates configuration is where you'll select the USPS Priority Mail Flat Rate service method from a dropdown menu.

After completing this configuration, you can designate USPS Priority Mail Flat Rate as your shipping method.

Designate USPS Priority Mail Flat Rate as your shipping method

USPS Priority Mail Flat Rate allows you to use designated packaging and pay one flat rate. The maximum allowed weight is 70 pounds.

To use USPS's packaging for the Priority Mail Flat Rate, you'll need to designate the type of USPS Priority Mail Flat Rate packaging that you wish to use. The following is a snippet of a JSON request call to Shipium's APIs. The minimum required fields for successfully selecting a USPS Priority Mail Flat Rate delivery method are included in the sample request and are defined in the table below. These fields are included in the shipmentParameters or multiParcelShipmentParameters of the call.

JSON

"packagingType": {
        "packagingMaterial": "usps_large_box"
      },
      "totalWeight": {
        "weightUnit": "lb",
        "weight": 0.5
Request field Details
shipmentParameters.packagingType .packagingMaterial Type: String (enumeration)
Values:usps_large_box, usps_large_box_to_apo_fpo_dpo, usps_medium_box, usps_small_box, usps_legal_envelope, usps_envelope, usps_padded_envelope
Description: The applicable USPS Priority Mail Flat Rate packaging type should be included as the packagingMaterial value.
shipmentParameters.packagingType .totalWeight.weightUnit Type: String (enumeration)
Values:g (gram), kg (kilogram), lb (pound), oz (ounce)
Description: The unit in which weight values are provided
shipmentParameters.packagingType .totalWeight.weight Type: Number (float)
Example:50
Description: The value of the weight; weight is limited to 70 pounds using the USPS Priority Mail Flat Rate service method.

Letter mail

If you'd like to send letter mail via USPS Direct's first-class mail service, you'll need to include a value of letters as the type of packaging material when using USPS's Priority Mail or Priority Mail Express service method. You'll also need to specify one of the supported service methods in your call. Size and weight restrictions apply:

In some instances, letter mail may qualify for USPS's Ground Advantage service method. You can find more information in the Letter Mail with Ground Advantage Service Method section.

The following is a snippet of a JSON request call to Shipium's APIs. The minimum required fields for successfully selecting the letter mail service method are included in the sample request and are defined in the table below. These fields are included in the shipmentParameters or multiParcelShipmentParameters of the call.

JSON

{
  ...
"shipmentParameters": {
    ...
   "packagingType": {
        "packagingMaterial": "letters"
      },
        "totalWeight": {
           "weightUnit": "oz",
           "weight": 0.5
        },
  ...
  "carrierServiceMethodAllowList": [\
    "usps-direct-priority-mail-service-method",\
    "usps-direct-priority-mail-express-service-method",\
    "usps-direct-priority-mail-international-service-method",\
    "usps-direct-priority-mail-express-international-service-method"\
    ],
  ...
}
Request field Details
shipmentParameters.packagingType .packagingMaterial Type: String (enumeration)
Value:letters
Description: For letter mail, letters should be included as the packagingMaterial value.
shipmentParameters.packagingType .totalWeight.weightUnit Type: String (enumeration)
Values:g (gram), kg (kilogram), lb (pound), oz (ounce)
Description: The unit in which weight values are provided
shipmentParameters.packagingType .totalWeight.weight Type: Number (float)
Example:1.5
Description: The value of the weight; weight is limited to 3.5 ounces for letter mail.
shipmentParameters .carrierServiceMethodAllowList Type: String (enumeration)
Description: Letter mail is only supported via Priority Mail and Priority Mail Express service methods. You can find a list of carrier service method IDs in Supported Carriers, and Specify Carrier Service and Method provides more information about including only certain service methods in your API calls.

Letter mail with Ground Advantage service method

USPS Ground Advantage typically is designated for shipping packages and certain types of large or irregular mail, not standard letters. However, letter mail could qualify for Ground Advantage based on its size, shape, and rigidity. When the following conditions are met, the item is treated as a package and it qualifies for Ground Advantage:

The following table summarizes which letter types might qualify for Ground Advantage. Letter mail that meets standard letter size and thickness requirements cannot be sent via Ground Advantage. It must be sent using First-Class Mail or other letter-specific services, as described in the previous section.

Letter type Qualifies for Ground Advantage? Notes
Standard flexible letter ✳️ No Use First-Class Mail
Large envelope (> 11.5 in x 6.125 in x 0.25 in) Yes Must be sent as a package
Rigid envelope (cannot bend) Yes Must be sent as a package
Lumpy / non-uniform envelope Yes Must be sent as a package
Letter with tracking/insurance needs No (unless above apply) Consider Certified Mail or Priority Mail for tracking

✳️ A standard flexible letter has a minimum length of 5 in and maximum length of 11-1/2 in; minimum height of 3-1/2 in and maximum height of 6-1/8 in; and minimum thickness of 0.007 in and maximum thickness of 1/4 in.

USPS via Endicia

USPS service methods via Endicia and their identifiers are listed on the Supported Carriers page.

Shipping options with USPS via Endicia

Packaging types

Letter mail via Endicia

If you'd like to send letter mail using USPS's first-class mail service via Endicia, you'll need to include a value of envelope as the type of packaging material and select a Priority Mail or Priority Mail Express service method. You'll also need to specify one of the supported service methods in your call. Size and weight restrictions apply:

In some instances, letter mail may qualify for USPS's Ground Advantage service method via Endicia. You can find more information in the Letter Mail with Ground Advantage Service Method via Endicia section.

JSON

/ {
  ...
"shipmentParameters": {
    ...
   "packagingType": {
        "packagingMaterial": "envelope"
      },
        "totalWeight": {
           "weightUnit": "oz",
           "weight": 0.5
        },
  ...
  "carrierServiceMethodAllowList": [\
    "usps-priority-mail-service-method",\
    "usps-priority-mail-express-service-method",\
    "usps-priority-mail-international-service-method",\
    "usps-priority-mail-express-international-service-method"\
    ],
  ...
}
Request field Details
shipmentParameters.packagingType .packagingMaterial Type: String (enumeration)
Value:envelope
Description: For letter mail, envelope should be included as the packagingMaterial value.
shipmentParameters.packagingType .totalWeight.weightUnit Type: String (enumeration)
Values:g (gram), kg (kilogram), lb (pound), oz (ounce)
Description: The unit in which weight values are provided
shipmentParameters.packagingType .totalWeight.weight Type: Number (float)
Example:1.5
Description: The value of the weight; weight is limited to 3.5 ounces for letter mail.
shipmentParameters .carrierServiceMethodAllowList Type: String (enumeration)
Description: Letter mail is only supported via Priority Mail and Priority Mail Express service methods. You can find a list of carrier service method IDs in Supported Carriers, and Specify Carrier Service and Method provides more information about including only certain service methods in your API calls.

Letter mail with Ground Advantage service method via Endicia

USPS Ground Advantage typically is designated for shipping packages and certain types of large or irregular mail, not standard letters. However, letter mail could qualify for Ground Advantage when shipping with Endicia based on its size, shape, and rigidity. When the following conditions are met, the item is treated as a package and it qualifies for Ground Advantage:

Letter type Qualifies for Ground Advantage? Notes
Standard flexible letter ✳️ No Use First-Class Mail
Large envelope (> 11.5 in x 6.125 in x 0.251 in) Yes Must be sent as a package; the envelope's thickness must exceed 0.25 in.
Rigid envelope (cannot bend) Yes Must be sent as a package
Lumpy / non-uniform envelope Yes Must be sent as a package
Letter with tracking/insurance needs No (unless above apply) Consider Certified Mail or Priority Mail for tracking

USPS via Pitney Bowes

Pitney Bowes offers two types of service methods through Shipium: Expedited service methods that serve as a proxy for USPS, and Presort service methods that use Pitney Bowes' own shipping resources for flats and marketing mail.

USPS service methods via Pitney Bowes and their identifiers are listed on the Supported Carriers page.

Credential types

When configuring Pitney Bowes in the Shipium Console, you'll select from two credential options based on the service methods you plan to use.

Configure Pitney Bowes for your account

To set up a carrier contract for Pitney Bowes, you'll need to access the Shipium Console and follow instructions for adding a carrier contract to a fulfillment context. If your organization doesn't use fulfillment contexts for configuration, you can use the fulfillment configuration workflow.

For either approach, once you reach the step to edit or add a carrier account for Pitney Bowes, you'll be asked to select a credential type and enter the required fields.

Standard Credentials

Select Pitney Bowes Standard Credentials from the dropdown menu if you're using Pitney Bowes Expedited service methods. All fields are required unless noted as optional.

Presort Credentials

Select Pitney Bowes Presort Credentials from the dropdown menu if you're using Pitney Bowes Presort service methods for flats or marketing mail. All fields are required unless noted as optional.