> ## 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. # Render an email message as HTML > Render an email message as HTML for an immediate preview. Render an email message as HTML without sending it. The HTML is the same as the body of a preview email. 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. A variable without a value uses its fallback, or shows a missing-value marker as in a preview email. The HTML has no open tracking pixel. As in a preview email, the unsubscribe link opens a page that does not unsubscribe anyone. ## OpenAPI ````yaml https://app.loops.so/openapi.json post /v1/email-messages/{emailMessageId}/render 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}/render: parameters: - name: emailMessageId in: path required: true description: The ID of the email message. schema: type: string examples: - cle5f7g9h1i3j5k7l9m1n3p5 post: tags: - Email messages summary: Render an email message as HTML description: >- Render the HTML of an email message the way its preview email is rendered. Nothing is sent. The accepted variable fields are the same as for previews - campaigns accept `contactProperties`, workflows accept `contactProperties` and `eventProperties`, and transactional emails accept `dataVariables`. A variable without a value uses its fallback, or shows a missing-value marker as in a preview email. Supplying a field the parent cannot reference is rejected with 400. operationId: renderEmailMessage requestBody: required: false content: application/json: schema: $ref: '#/components/schemas/EmailMessageRenderRequest' examples: campaign: summary: Campaign email value: contactProperties: firstName: Alex workflow: summary: Workflow email value: contactProperties: firstName: Alex eventProperties: planName: Pro transactional: summary: Transactional email value: dataVariables: loginUrl: https://app.company.com/login responses: '200': description: Rendered email message. content: application/json: schema: $ref: '#/components/schemas/EmailMessageRenderResponse' '400': description: >- Invalid request body, a variable field the parent cannot reference, a sending domain without a domain or address, or a from or reply-to address that renders to an invalid email. 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. security: - apiKey: [] components: schemas: EmailMessageRenderRequest: type: object properties: contactProperties: type: object additionalProperties: type: string description: >- Contact property values to render. Accepted for campaign and workflow emails. example: firstName: Alex eventProperties: type: object additionalProperties: type: string description: Event property values to render. Accepted for workflow emails only. example: planName: Pro dataVariables: type: object additionalProperties: type: string description: >- Transactional data variables to render. Accepted for transactional emails only. example: loginUrl: https://app.company.com/login additionalProperties: false EmailMessageRenderResponse: type: object properties: html: type: string description: >- The rendered HTML. For emails made in the editor, it includes the rendered subject in `` and the rendered preview text. examples: - <!doctype html><html>...</html> required: - html examples: - html: <!doctype html><html>...</html> 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 - [Send a preview of an email message](https://loops.so/docs/api-reference/preview-email-message.md) - [Email messages](https://loops.so/docs/cli/email-messages.md) - [Why we don't support HTML emails](https://loops.so/docs/guides/html-emails.md) - [Get an email message](https://loops.so/docs/api-reference/get-email-message.md) - [Update an email message](https://loops.so/docs/api-reference/update-email-message.md)