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

# Introduction

> High-performance email infrastructure. Manage design assets, audience segments, and delivery schedules via a unified API.

## Welcome

All API clusters are hosted on managed instances with SSL/TLS 1.3 encryption.

<CardGroup cols={2}>
  <Card title="Environment" icon="server">
    Base URL: `https://api.syntr.io/api/v1/email-marketing`
  </Card>

  <Card title="Protocols" icon="bolt">
    Content-Type: `application/json`
  </Card>
</CardGroup>

## Authentication

Unique access tokens generated in your dashboard. Enforces granular module permissions.

```http theme={null}
X-API-Key: [YOUR_KEY]
```

## Status Codes

| Code  | Label         | Description                                       |
| :---- | :------------ | :------------------------------------------------ |
| `200` | Request OK    | Operation completed successfully.                 |
| `401` | Invalid Token | API key is missing or has been expired.           |
| `403` | Access Denied | Operation blocked due to scope restrictions.      |
| `422` | Payload Error | Invalid JSON structure or business logic failure. |