> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lerian.studio/llms.txt
> Use this file to discover all available pages before exploring further.

# Download attachment

> Streams an attachment file (application/octet-stream). Emits a DOWNLOAD_ATTACHMENT audit event.



## OpenAPI

````yaml /en/openapi/v3-current/bc-correios.yaml get /api/v1/correios/mails/{id}/attachments/{attachmentId}
openapi: 3.1.0
info:
  description: >-
    API for Lerian BC Correios, which connects the institution to BC Correio,
    Banco Central do Brasil's electronic correspondence system. It retrieves and
    stores the institution's BC Correio mail, sends messages to BACEN
    departments, and keeps an audit trail.
  title: Lerian BC Correios API
  version: 1.0.0
servers:
  - url: https://bc-correios.sandbox.lerian.net
security:
  - BearerAuth: []
tags:
  - description: Mail listing, search, read, send, and lifecycle operations.
    name: Mails
  - description: Immutable audit-trail query and export.
    name: Audit
  - description: 'Per-tenant configuration: BCB credentials, polling, AI, retention.'
    name: Settings
  - description: Aggregate mail metrics and category breakdowns.
    name: Dashboard
paths:
  /api/v1/correios/mails/{id}/attachments/{attachmentId}:
    get:
      tags:
        - Mails
      summary: Download attachment
      description: >-
        Streams an attachment file (application/octet-stream). Emits a
        DOWNLOAD_ATTACHMENT audit event.
      operationId: GetAttachment
      parameters:
        - description: Mail ID (UUID v4)
          in: path
          name: id
          required: true
          schema:
            description: Mail ID (UUID v4)
            examples:
              - 550e8400-e29b-41d4-a716-446655440000
            type: string
        - description: Attachment ID (UUID v4)
          in: path
          name: attachmentId
          required: true
          schema:
            description: Attachment ID (UUID v4)
            examples:
              - 660e8400-e29b-41d4-a716-446655440111
            type: string
      responses:
        '200':
          content:
            application/octet-stream:
              schema:
                contentMediaType: application/octet-stream
                format: binary
                type: string
          description: >-
            Attachment bytes, streamed with the stored MIME type and a
            Content-Disposition: attachment header.
        '400':
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/Detail'
          description: Bad Request
        '401':
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/Detail'
          description: Unauthorized
        '404':
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/Detail'
          description: Not Found
        '422':
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/Detail'
          description: Unprocessable Entity
        '429':
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/Detail'
          description: Too Many Requests
        '500':
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/Detail'
          description: Internal Server Error
        '503':
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/Detail'
          description: Service Unavailable
      security:
        - BearerAuth: []
components:
  schemas:
    Detail:
      additionalProperties: false
      properties:
        code:
          description: >-
            Stable, machine-readable domain error code scoped to the emitting
            service (format: <SERVICE>-NNNN).
          type: string
        correlationId:
          description: Request-scoped correlation identifier echoing X-Request-ID.
          examples:
            - req-7a3f9c2e
          type: string
        detail:
          description: >-
            A human-readable explanation specific to this occurrence of the
            problem.
          examples:
            - Property foo is required but is missing.
          type: string
        errors:
          description: Optional list of individual error details
          items:
            $ref: '#/components/schemas/ErrorDetail'
          type:
            - array
            - 'null'
        instance:
          description: >-
            A URI reference that identifies the specific occurrence of the
            problem.
          examples:
            - https://example.com/error-log/abc123
          format: uri
          type: string
        status:
          description: HTTP status code
          examples:
            - 400
          format: int64
          type: integer
        title:
          description: >-
            A short, human-readable summary of the problem type. This value
            should not change between occurrences of the error.
          examples:
            - Bad Request
          type: string
        type:
          default: about:blank
          description: A URI reference to human-readable documentation for the error.
          examples:
            - https://example.com/errors/example
          format: uri
          type: string
        upstream:
          $ref: '#/components/schemas/Upstream'
          description: >-
            RFC 9457 extension member: the error a proxied third-party provider
            reported. Absent unless the emitting service explicitly surfaced
            one.
      required:
        - correlationId
      type: object
    ErrorDetail:
      additionalProperties: false
      properties:
        location:
          description: >-
            Where the error occurred, e.g. 'body.items[3].tags' or
            'path.thing-id'
          type: string
        message:
          description: Error message text
          type: string
        value:
          description: The value at the given location
      type: object
    Upstream:
      additionalProperties: false
      properties:
        code:
          description: The upstream provider's own error code, verbatim.
          examples:
            - E4001
          type: string
        message:
          description: >-
            The upstream provider's own error message, verbatim (bounded, never
            its raw response body).
          examples:
            - account not found at provider
          type: string
      type: object
  securitySchemes:
    BearerAuth:
      bearerFormat: JWT
      description: JWT bearer token issued by the identity provider.
      scheme: bearer
      type: http

````

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