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

# Transactional Email API

> Send transactional emails using custom HTML or pre-built templates

## Overview

The Flywheel Transactional Email API allows you to send emails programmatically to your users. There are two main ways to send transactional emails:

1. **Custom emails** - Send emails with custom HTML content, text, and full control over email properties
2. **Template emails** - Send emails using pre-built templates with dynamic variables

## Authentication

All transactional email endpoints require authentication using an API key and authentication type header. Include both headers in your requests:

```
Authorization: YOUR_API_KEY
Auth-Type: api
```

Both headers are required for all API requests.

## Endpoints

The following endpoints are available with interactive API playground for testing:

<CardGroup cols={2}>
  <Card title="Send Custom Email" icon="mail" href="/POST/v1/transactional/custom">
    Send emails with custom HTML content and full control over email properties
  </Card>

  <Card title="Send Template Email" icon="file-text" href="/POST/v1/transactional/template">
    Send emails using pre-built templates with dynamic variables
  </Card>
</CardGroup>

## Interactive API Playground

All endpoints include an interactive playground where you can test API calls directly from the documentation. The playground includes:

* **Live testing**: Send real API requests with your authentication token
* **Code examples**: Auto-generated code snippets in multiple languages (cURL, JavaScript, Python, PHP)
* **Request/Response validation**: Real-time validation of request parameters and response formats
* **Authentication testing**: Test with your actual API credentials in a secure environment

## Email Delivery

All emails are sent through our reliable email infrastructure powered by Resend. You'll receive an email ID in the response that you can use to track delivery status.

## Rate Limits

Transactional email endpoints are subject to rate limiting to ensure fair usage and service reliability. Contact support if you need higher limits for your use case.

## Support

For questions about the Transactional Email API, contact our support team at [support@flywheel.cx](mailto:support@flywheel.cx).