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OpenAPI Specification

openapi: 3.2.0
info:
  title: JustEmails Send API
  version: 1.0.0
  description: REST API for JustEmails — unlimited-domain email hosting + transactional email. This spec is consumable by ChatGPT Custom GPTs, Zapier, n8n, Make, and any OpenAPI-aware tool. The same capabilities are also exposed via MCP at https://mcp.justemails.app/mcp for AI clients like Claude Desktop / Cursor / VS Code.
  contact:
    name: JustEmails
    url: https://justemails.app
  license:
    name: Proprietary
  termsOfService: https://justemails.app/terms
servers:
- url: https://justemails.app
  description: Production
security:
- bearerAuth: []
tags:
- name: Send
paths:
  /api/v1/send:
    post:
      operationId: sendTransactional
      summary: Send a transactional email
      tags:
      - Send
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SendTransactionalRequest'
      responses:
        '200':
          description: Enqueued for delivery
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    type: object
                    properties:
                      id:
                        type: string
                  meta:
                    type: object
                    additionalProperties: true
                required:
                - data
        '429':
          description: Rate limited
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /api/v1/messages:
    get:
      operationId: listMessages
      summary: List transactional messages
      tags:
      - Send
      parameters:
      - name: status
        in: query
        schema:
          type: string
      - name: tag
        in: query
        schema:
          type: string
      - name: cursor
        in: query
        schema:
          type: string
      - name: limit
        in: query
        schema:
          type: integer
          minimum: 1
          maximum: 100
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    type: array
                    items:
                      $ref: '#/components/schemas/Message'
                  meta:
                    type: object
                    additionalProperties: true
                required:
                - data
  /api/v1/messages/{id}:
    get:
      operationId: getMessage
      summary: Get message status + event history
      tags:
      - Send
      parameters:
      - name: id
        in: path
        required: true
        schema:
          type: string
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    $ref: '#/components/schemas/Message'
                  meta:
                    type: object
                    additionalProperties: true
                required:
                - data
components:
  schemas:
    Error:
      type: object
      properties:
        error:
          type: object
          properties:
            code:
              type: string
            message:
              type: string
            details: {}
          required:
          - code
          - message
    Message:
      type: object
      properties:
        id:
          type: string
        status:
          type: string
          enum:
          - queued
          - sent
          - delivered
          - bounced
          - complained
          - opened
          - clicked
          - failed
        createdAt:
          type: string
          format: date-time
        events:
          type: array
          items:
            type: object
            properties:
              type:
                type: string
              at:
                type: string
                format: date-time
              detail:
                type: string
    SendTransactionalRequest:
      type: object
      required:
      - from
      - to
      - subject
      properties:
        from:
          type: string
          format: email
          description: Sender address on a verified domain.
        to:
          oneOf:
          - type: string
            format: email
          - type: array
            items:
              type: string
              format: email
            minItems: 1
        cc:
          oneOf:
          - type: string
            format: email
          - type: array
            items:
              type: string
              format: email
        bcc:
          oneOf:
          - type: string
            format: email
          - type: array
            items:
              type: string
              format: email
        subject:
          type: string
          maxLength: 998
        html:
          type: string
          maxLength: 2000000
        text:
          type: string
          maxLength: 2000000
        replyTo:
          type: string
          format: email
        idempotencyKey:
          type: string
          maxLength: 255
        trackOpens:
          type: boolean
          description: 'Open tracking for this send (1x1 image in the HTML part). Omit for the account default, which is off. Approximate: Apple Mail Privacy Protection and image proxies load images without a reader.'
        trackClicks:
          type: boolean
          description: Click tracking for this send (HTML links rewritten to a signed justemails.app redirect; plain text untouched). Omit for the account default, which is off.
        tags:
          type: array
          items:
            type: string
            maxLength: 64
          maxItems: 10
        headers:
          type: object
          additionalProperties:
            type: string
          description: 'Custom headers, one line each. Not allowed: From, To, Cc, Bcc, Subject, Date, Message-ID, DKIM-Signature (use the from, to, cc, bcc and subject fields), nor "key" and "value" together.'
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: opaque
      description: 'Create an API key at https://justemails.app/settings/api-keys and pass as `Authorization: Bearer <key>`.'
externalDocs:
  description: Full MCP tool catalog + integration guides
  url: https://mcp.justemails.app/docs