> ## Documentation Index > Fetch the complete documentation index at: https://docs.paubox.com/llms.txt > Use this file to discover all available pages before exploring further. # Update a campaign > Updates a campaign mailing. Only the fields you send are changed. `PUT` is accepted as an equivalent to `PATCH`. `subject` must stay unique within your account. The unsubscribe footer is reapplied to `html_part` on every save. **Example curl command:** ```bash curl -X PATCH \ https://api.paubox.com/v1/marketing/campaign_mailings/123e4567-e89b-12d3-a456-426614174000 \ -H 'authorization: Token token=YOUR_API_KEY' \ -H 'content-type: application/json' \ -d '{ "campaign_mailing": { "subject": "March newsletter (revised)" } }' ``` ## OpenAPI ````yaml openapi2 PATCH /campaign_mailings/{campaign_mailing_id} openapi: 3.0.3 info: title: Paubox Marketing API description: > Public documentation Paubox Marketing API. All Paubox Marketing customers have access to the Paubox Marketing API to automate various tasks. ## Authentication Use the authorization header in requests with the format: `authorization: Token token=` Replace `` with your API key. Find your API key in the address bar from the email builder (note: each API Key is displayed only once upon creation). ## Base URL `https://api.paubox.com/v1/marketing` contact: name: Paubox Support url: https://www.paubox.com version: 1.0.0 servers: - url: https://api.paubox.com/v1/marketing description: Production server security: - TokenAuth: [] tags: - name: subscribers description: Subscriber management operations - name: analytics description: Campaign analytics and reporting operations - name: campaign_mailings description: Campaign mailing management and sending operations - name: drip_campaigns description: Drip campaign management and automation operations - name: subscription_lists description: Subscription list management operations - name: subscriptions description: Subscriber opt-in and opt-out operations - name: tracking_links description: Tracking link analytics and data operations paths: /campaign_mailings/{campaign_mailing_id}: patch: tags: - campaign_mailings summary: Update a campaign mailing description: > Updates a campaign mailing. Only the fields you send are changed. `PUT` is accepted as an equivalent to `PATCH`. `subject` must stay unique within your account. The unsubscribe footer is reapplied to `html_part` on every save. **Example curl command:** ```bash curl -X PATCH \ https://api.paubox.com/v1/marketing/campaign_mailings/123e4567-e89b-12d3-a456-426614174000 \ -H 'authorization: Token token=YOUR_API_KEY' \ -H 'content-type: application/json' \ -d '{ "campaign_mailing": { "subject": "March newsletter (revised)" } }' ``` operationId: updateCampaignMailing parameters: - name: campaign_mailing_id in: path description: UUID of the campaign mailing required: true schema: type: string requestBody: content: application/json: schema: $ref: '#/components/schemas/UpdateCampaignMailingRequest' example: campaign_mailing: subject: March newsletter (revised) required: true responses: '200': description: >- The updated campaign mailing's ID. If validation fails the response is still `200` but the body contains an `errors` array instead of `data`. content: application/json: schema: $ref: '#/components/schemas/CampaignMailingWriteResponse' '401': $ref: '#/components/responses/Unauthorized' '404': $ref: '#/components/responses/NotFound' '500': $ref: '#/components/responses/InternalServerError' components: schemas: UpdateCampaignMailingRequest: type: object properties: campaign_mailing: $ref: '#/components/schemas/UpdateCampaignMailingRequest_campaign_mailing' CampaignMailingWriteResponse: type: object description: >- Returned with HTTP 200 in both the success and the validation-failure case. Check for the presence of `errors`. properties: data: $ref: '#/components/schemas/CampaignMailingWriteResponse_data' errors: type: array description: Validation messages, present only when the write failed items: type: string UpdateCampaignMailingRequest_campaign_mailing: type: object description: Only the fields supplied are changed. properties: subject: type: string description: Subject line. Must remain unique within your account. default_subject: type: string description: Fallback subject used when no subject is set on a send from: type: string description: From address for the mailing reply_to: type: string description: Reply-to address for the mailing html_part: type: string description: HTML body. The unsubscribe footer is reapplied on save. text_part: type: string description: Plain-text body form_data: type: string description: JSON-encoded editor state, for mailings built in an editor template_type: type: string description: >- Editor the mailing is authored in, for example `quill`, `bee` or `html` CampaignMailingWriteResponse_data: type: object properties: id: type: string description: UUID of the created or updated campaign mailing Error: type: object properties: error: type: string description: Error message code: type: string description: Error code details: type: object description: Additional error details responses: Unauthorized: description: Unauthorized content: application/json: schema: $ref: '#/components/schemas/Error' NotFound: description: Resource not found content: application/json: schema: $ref: '#/components/schemas/Error' InternalServerError: description: Internal server error content: application/json: schema: $ref: '#/components/schemas/Error' securitySchemes: TokenAuth: type: apiKey description: >- Token-based authentication. Use format: "Token token=" where is your API key name: authorization in: header ````