> ## Documentation Index > Fetch the complete documentation index at: https://loops.so/docs/llms.txt > Use this file to discover all available pages before exploring further. # Send a preview of an email message > Send a test preview of an email message to one or more addresses. Send a test email message to one or more addresses. Accepted variable fields depend on the parent's type: * **Campaign** accepts `contactProperties`. * **Workflow** accepts `contactProperties` and `eventProperties`. * **Transactional** accepts `dataVariables`. Supplying a field the parent cannot reference results in a `400 Bad Request` error. Each team can send up to 100 preview emails per day. ## OpenAPI ````yaml https://app.loops.so/openapi.json post /v1/email-messages/{emailMessageId}/preview openapi: 3.1.0 info: title: Loops OpenAPI Spec description: This is the OpenAPI Spec for the [Loops API](https://loops.so/docs/api). version: 1.23.0 servers: - url: https://app.loops.so/api security: [] tags: - name: API key - name: Audience segments description: View and create audience segments - name: Campaigns description: Create and manage email campaigns - name: Campaign groups description: Organize campaigns into groups - name: Configuration description: View configuration settings - name: Contacts description: Manage contacts in your audience - name: Contact properties description: Manage contact properties - name: Components description: View email components - name: Email messages description: Manage email message content for campaigns - name: Events description: Trigger workflows with events - name: Event patterns description: View workflow event patterns - name: Mailing lists description: View mailing lists - name: Themes description: View email themes - name: Transactional emails description: Create, manage, and send transactional emails - name: Transactional groups description: Organize transactional emails into groups - name: Uploads description: Upload image assets - name: Workflows description: View and mutate workflow graphs - name: Workflow groups description: Organize workflows into groups - name: Workflow nodes description: View and mutate workflow nodes - name: Webhooks description: >- Events Loops sends to your configured webhook endpoint when certain events happen in your account. Configure an endpoint in Settings → Webhooks. Each account supports one webhook endpoint. Events are signed with `webhook-id`, `webhook-timestamp`, and `webhook-signature` headers and delivered at a maximum rate of 10 per second. See https://loops.so/docs/webhooks for setup, verification, and payload details. paths: /v1/email-messages/{emailMessageId}/preview: parameters: - name: emailMessageId in: path required: true description: The ID of the email message. schema: type: string examples: - cle5f7g9h1i3j5k7l9m1n3p5 post: tags: - Email messages summary: Send a preview of an email message description: >- Send a test preview of an email message to one or more addresses. The accepted variable fields depend on the parent's type - campaign previews accept `contactProperties`, workflow previews accept `contactProperties` and `eventProperties`, and transactional previews accept `dataVariables`. Supplying a field the parent cannot reference is rejected with 400. operationId: previewEmailMessage requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/EmailMessagePreviewRequest' examples: campaign: summary: Campaign email value: emails: - alex@company.com contactProperties: firstName: Alex workflow: summary: Workflow email value: emails: - alex@company.com contactProperties: firstName: Alex eventProperties: planName: Pro transactional: summary: Transactional email value: emails: - alex@company.com dataVariables: loginUrl: https://app.company.com/login responses: '200': description: Preview scheduled. content: application/json: schema: $ref: '#/components/schemas/EmailMessagePreviewResponse' '400': description: >- Invalid request body, or a variable field the parent cannot reference. content: application/json: schema: $ref: '#/components/schemas/EmailMessageFailureResponse' '401': description: Invalid API key or content API not enabled for this team. '404': description: Email message not found. content: application/json: schema: $ref: '#/components/schemas/EmailMessageFailureResponse' '405': description: Wrong HTTP request method. '429': description: The daily preview limit was reached. content: application/json: schema: $ref: '#/components/schemas/EmailMessageFailureResponse' security: - apiKey: [] components: schemas: EmailMessagePreviewRequest: type: object properties: emails: type: array minItems: 1 items: type: string description: One or more addresses to send the preview to. contactProperties: type: object additionalProperties: type: string description: >- Contact property values to render. Accepted for campaign and workflow previews. example: firstName: Alex eventProperties: type: object additionalProperties: type: string description: >- Event property values to render. Accepted for workflow previews only. example: planName: Pro dataVariables: type: object additionalProperties: type: string description: >- Transactional data variables to render. Accepted for transactional previews only. example: loginUrl: https://app.company.com/login required: - emails additionalProperties: false EmailMessagePreviewResponse: type: object properties: id: type: string description: The ID of the email message the preview was sent for. examples: - cle5f7g9h1i3j5k7l9m1n3p5 required: - id examples: - id: cle5f7g9h1i3j5k7l9m1n3p5 EmailMessageFailureResponse: type: object properties: message: type: string required: - message examples: - message: Email message not found. - message: 'Workflow must not be sending. Current status: Sending.' securitySchemes: apiKey: type: http scheme: bearer ```` ## Related topics - [Email messages](https://loops.so/docs/cli/email-messages.md) - [Send a transactional email](https://loops.so/docs/api-reference/send-transactional-email.md) - [Supabase - Send emails](https://loops.so/docs/integrations/supabase/send-email.md) - [Transactional email API examples](https://loops.so/docs/api-reference/examples/transactional-emails.md) - [Campaigns API examples](https://loops.so/docs/api-reference/examples/campaigns.md)