PostalForm Webhook Events API

openapi: 3.2.0
info:
  title: PostalForm Projects Public Webhook Events API
  version: '2026-05-06'
  description: Public PostalForm Projects API for customer SDKs. Includes document uploads, quotes, mail orders, credits, API keys, and signed customer webhooks.
servers:
- url: https://projects.postalform.com
tags:
- name: Webhook Events
paths:
  /api/v1/webhook-events:
    get:
      summary: List customer webhook events for the workspace
      description: Customer webhook events are fulfillment status-change events only. Event names use `postalform.{letter|postcard}.{status}` and are emitted for `accepted`, `in_transit`, `delivered`, `returned`, `failed`, and `canceled`.
      security:
      - bearerAuth: []
      responses:
        '200':
          description: Events.
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    type: array
                    items:
                      $ref: '#/components/schemas/WebhookEvent'
      operationId: listWebhookEvents
      tags:
      - Webhook Events
  /api/v1/webhook-events/{event_id}/replay:
    post:
      summary: Queue a customer webhook event for replay
      security:
      - bearerAuth: []
      parameters:
      - $ref: '#/components/parameters/EventId'
      responses:
        '200':
          description: Replay queued.
      operationId: replayWebhookEvent
      tags:
      - Webhook Events
components:
  schemas:
    WebhookEvent:
      type: object
      properties:
        id:
          type: string
        workspaceId:
          type: string
        orderId:
          type: string
        eventType:
          $ref: '#/components/schemas/CustomerWebhookEventType'
        payload:
          $ref: '#/components/schemas/CustomerWebhookPayload'
        createdAt:
          type: string
          format: date-time
        deliveries:
          type: array
          items:
            $ref: '#/components/schemas/WebhookDeliveryAttempt'
    CustomerWebhookPayload:
      type: object
      description: JSON body POSTed to customer webhook endpoints.
      properties:
        id:
          type: string
          example: evt_123
        type:
          $ref: '#/components/schemas/CustomerWebhookEventType'
        data:
          type: object
          properties:
            object:
              $ref: '#/components/schemas/Letter'
        mailpiece:
          type: object
          properties:
            status:
              type: string
              nullable: true
            tracking_number:
              type: string
              nullable: true
            tracking_status:
              type: string
              nullable: true
    MailOrderStatus:
      type: string
      enum:
      - queued
      - document_preparing
      - document_prepared
      - submitted
      - accepted
      - in_transit
      - delivered
      - returned
      - submission_pending
      - failed
      - canceled
      description: Order timeline status. `submission_pending` means the fulfillment submit job entered a physical-mail safety window where PostalForm cannot blindly retry without risking duplicate mail; it requires reconciliation if it remains the current order status.
    Mode:
      type: string
      enum:
      - test
      - live
    WebhookDeliveryAttempt:
      type: object
      properties:
        id:
          type: string
        webhookEventId:
          type: string
        endpointId:
          type: string
        attemptNumber:
          type: integer
        status:
          type: string
          enum:
          - succeeded
          - failed
        httpStatus:
          type: integer
        responseBodySnippet:
          type: string
        attemptedAt:
          type: string
          format: date-time
        nextRetryAt:
          type: string
          format: date-time
    CustomerWebhookEventType:
      type: string
      description: Customer webhook event names emitted for fulfillment status changes. Replace `letter` with `postcard` for postcard mailpieces.
      enum:
      - postalform.letter.accepted
      - postalform.letter.in_transit
      - postalform.letter.delivered
      - postalform.letter.returned
      - postalform.letter.failed
      - postalform.letter.canceled
      - postalform.postcard.accepted
      - postalform.postcard.in_transit
      - postalform.postcard.delivered
      - postalform.postcard.returned
      - postalform.postcard.failed
      - postalform.postcard.canceled
      x-enumDescriptions:
        postalform.letter.accepted: Letter accepted for production or mailing after the order leaves PostalForm's preparation queue.
        postalform.letter.in_transit: Letter entered the mail stream. The payload may include or update `mailpiece.tracking_number` when tracking is available.
        postalform.letter.delivered: Letter reported delivered by the carrier or delivery network.
        postalform.letter.returned: Letter returned or otherwise marked undeliverable.
        postalform.letter.failed: Letter could not be produced or mailed. Inspect the order timeline and retry with a corrected request when appropriate.
        postalform.letter.canceled: Letter canceled before delivery completion.
        postalform.postcard.accepted: Postcard accepted for production or mailing after the order leaves PostalForm's preparation queue.
        postalform.postcard.in_transit: Postcard entered the mail stream. The payload may include or update `mailpiece.tracking_number` when tracking is available.
        postalform.postcard.delivered: Postcard reported delivered by the carrier or delivery network.
        postalform.postcard.returned: Postcard returned or otherwise marked undeliverable.
        postalform.postcard.failed: Postcard could not be produced or mailed. Inspect the order timeline and retry with a corrected request when appropriate.
        postalform.postcard.canceled: Postcard canceled before delivery completion.
    Letter:
      type: object
      properties:
        id:
          type: string
        object:
          type: string
          enum:
          - letter
          - postcard
        mailpiece_type:
          type: string
          enum:
          - letter
          - postcard
        postcard_size:
          type:
          - string
          - 'null'
          enum:
          - 4x6
          - 6x9
          - 11x6
          - null
        status:
          $ref: '#/components/schemas/MailOrderStatus'
        mode:
          $ref: '#/components/schemas/Mode'
        price_cents:
          type: integer
        currency:
          type: string
        funds_status:
          type: string
        billing_rail:
          type: string
        tracking_number:
          type: string
          nullable: true
          description: Carrier tracking number when available.
        tracking_url:
          type:
          - string
          - 'null'
          format: uri
          description: Direct USPS tracking URL when a tracking number is available. Manual ERR customers can use it to request their receipt from USPS.
        tracking_status:
          type: string
          nullable: true
          description: Normalized tracking status when available.
        return_receipt_format:
          type: string
          enum:
          - electronic
          - physical
        restricted_delivery:
          type: boolean
        err_delivery:
          type: string
          enum:
          - manual
          - email
        err_email:
          type:
          - string
          - 'null'
          format: email
        err_status:
          type: string
          enum:
          - manual
          - pending
          - sent
          - failed
          - expired
        err_delivered_at:
          type:
          - string
          - 'null'
          format: date-time
        err_retention_until:
          type:
          - string
          - 'null'
          format: date-time
          description: Last instant at which an acquired receipt remains retrievable. PostalForm's default ERR retention is three years.
        return_receipt_available:
          type: boolean
          description: Whether a stored electronic receipt can currently be downloaded.
        return_receipt_url:
          type:
          - string
          - 'null'
          description: Relative authenticated download URL when return_receipt_available is true.
        metadata:
          type: object
          additionalProperties: true
        created_at:
          type: string
          format: date-time
        updated_at:
          type: string
          format: date-time
        idempotent_replay:
          type: boolean
  parameters:
    EventId:
      name: event_id
      in: path
      required: true
      schema:
        type: string
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer