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

# Add to suppression list

> Add an email address to the suppression list. Suppressed emails will not receive any emails. If the email already exists in the suppression list, the existing entry is returned with a `200` status code. The email is normalized to lowercase.



## OpenAPI

````yaml POST /suppressions
openapi: 3.1.0
info:
  title: SendKit API
  description: The SendKit API allows you to send transactional emails programmatically.
  version: 1.0.0
servers:
  - url: https://api.sendkit.dev
security:
  - bearerAuth: []
paths:
  /suppressions:
    post:
      tags:
        - Suppressions
      summary: Add to suppression list
      description: >-
        Add an email address to the suppression list. Suppressed emails will not
        receive any emails. If the email already exists in the suppression list,
        the existing entry is returned with a `200` status code. The email is
        normalized to lowercase.
      operationId: createSuppression
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateSuppressionRequest'
      responses:
        '200':
          description: Email already exists in the suppression list
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Suppression'
        '201':
          description: Email added to the suppression list
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Suppression'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
components:
  schemas:
    CreateSuppressionRequest:
      type: object
      required:
        - email
      properties:
        email:
          type: string
          format: email
          maxLength: 255
          description: The email address to suppress.
          example: blocked@example.com
    Suppression:
      type: object
      properties:
        id:
          type: string
          format: uuid
          description: Unique identifier for the suppression entry.
        email:
          type: string
          format: email
          description: The suppressed email address.
        reason:
          type:
            - string
            - 'null'
          enum:
            - manual
            - bounce
            - complaint
            - null
          description: The reason the email was suppressed.
        created_at:
          type: string
          description: When the entry was created.
          example: '2026-03-03 10:00:00'
        updated_at:
          type: string
          description: When the entry was last updated.
          example: '2026-03-03 10:00:00'
      required:
        - id
        - email
        - created_at
        - updated_at
    ErrorResponse:
      type: object
      properties:
        name:
          type: string
          description: Error type identifier.
          example: validation_error
        message:
          type: string
          description: Human-readable error message.
          example: The from address domain is not verified.
  responses:
    Unauthorized:
      description: Unauthorized — missing or invalid API key
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
          example:
            message: Invalid API key.
    ValidationError:
      description: Validation error — invalid or missing parameters
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
          example:
            message: The email field is required.
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: >-
        API key from your SendKit dashboard. Pass it as a Bearer token in the
        Authorization header.

````