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

# Authentication

> Authenticate with Bearer and your Secret Key in the Authorization header.

Every endpoint uses the same method: **Bearer Token** with your Secret Key.

***

## Bearer Token

Send your **Secret Key** (`sk_proj_...`) in the `Authorization` header:

```
Authorization: Bearer sk_proj_your_secret_key
```

This pattern works for **all** endpoints:

* **Sending:** `POST /v1/send-email`, `POST /v1/send-template-email`, `POST /v1/send-batch`, `POST /send-email`
* **Domains:** `POST /domains/register`, `GET /domains/:domain/dns-records`, `POST /domains/:domain/verify`, `GET /domains/:domain/status`, `GET /domains?domain=`, `POST /domains/:domain/recreate`, `DELETE /domains/:domain`, `PUT /domains/:domain/sender`, `POST /domains/verify-email`, `GET /domains/verify-email/status`
* **Activity:** `GET /v1/activity`, `GET /v1/activity/:id`
* **Data:** `POST /v1/leads`, `POST /v1/events` (and the rest of the [leads and events API](/en/api-reference/leads))

### Example

```bash theme={null}
curl -X POST https://api.reallyquickemails.com/v1/send-email \
  -H "Authorization: Bearer sk_proj_your_secret_key" \
  -H "Content-Type: application/json" \
  -d '{
    "recipient_email": "customer@example.com",
    "sender_email": "sales@yourdomain.com",
    "subject": "Order confirmation",
    "html_body": "<h1>Order confirmed</h1>"
  }'
```

### How it works

1. The server extracts the Secret Key from the `Authorization` header
2. It validates the key and resolves the associated project
3. If the key is valid, the `projectId` is derived automatically — you don't need to send it

***

## Where to find your Secret Key

1. Log in to the [RQE dashboard](https://app.reallyquickemails.com).
2. Select your project.
3. In the sidebar, open **Integrations → API Keys**.
4. Copy your **Secret Key** (it starts with `sk_proj_`).

There you'll also find the **Test key** (`sk_test_*`). See [API Keys](/en/guides/api-keys) for the differences between Live and Test mode.

***

## Error responses

**Missing key or incorrect format (401):**

```json theme={null}
{
  "error": "Missing or invalid API key. Use: Authorization: Bearer sk_proj_..."
}
```

**Invalid key (401):**

```json theme={null}
{
  "error": "Invalid API key"
}
```

***

## Common errors

| Code  | Cause                                                   | Solution                                                        |
| ----- | ------------------------------------------------------- | --------------------------------------------------------------- |
| `401` | Missing `Authorization` header                          | Add `Authorization: Bearer sk_proj_...`                         |
| `401` | Incorrect format (no "Bearer " or missing `sk_` prefix) | Make sure to use `Bearer sk_proj_...` with a space              |
| `401` | Invalid or revoked key                                  | Regenerate it from **Integrations → API Keys** in the dashboard |