# Send newsletter

> Sends a newsletter now, or schedules it, to every contact with a confirmed opt-in inside its audience; unsubscribed contacts never receive it. Needs an approved template and an idempotency key. Sending cannot be undone once started.

Last updated: 2026-10-25. Source: https://docs.smartchat.marketing/en/api/reference/newsletters/send_newsletter/

Sends a newsletter now, or schedules it, to every contact with a confirmed opt-in inside its audience; unsubscribed contacts never receive it. Needs an approved template and an idempotency key. Sending cannot be undone once started.

`POST /v1/newsletters/{newsletter_id}/send`

| | |
|---|---|
| Permission | `newsletters:send` ([all permissions](https://docs.smartchat.marketing/en/api/permissions/)) |
| Risk | Send (reaches other people) |
| Idempotency-Key | Required ([how it works](https://docs.smartchat.marketing/en/concepts/idempotency/)) |
| Safe to repeat | Safe to repeat with the same Idempotency-Key: the first answer comes back and nothing is done twice. |
| Rate limit class | `send` (120 requests per minute per key) |
| Confirmation | None |
| MCP tool | [`send_newsletter`](https://docs.smartchat.marketing/en/mcp/tools/send_newsletter/) |
| Since version | 2026-10-25 |

## What it does

- Sends WhatsApp messages to contacts.
- Safe to repeat with the same Idempotency-Key.

> **Important** Messages are only sent to contacts who may receive them. The server checks the opt-in, never sends to unsubscribed contacts, respects the 24-hour window and uses approved templates only. See [Sending safely](https://docs.smartchat.marketing/en/security/).

## Request

**Header**

| Name | Required | Description |
|---|---|---|
| `Authorization` | yes | `Bearer <key>` |
| `Idempotency-Key` | yes | A unique value for this operation, for example a UUID (1 to 255 visible ASCII characters). |

**Path parameters**

| Name | Type | Description |
|---|---|---|
| `newsletter_id` | string | ID of the newsletter, from list_newsletters. |

**Body** (JSON)

| Name | Type | Required | Description |
|---|---|---|---|
| `when` | string | yes | 'now' or a time in ISO 8601, for example 2026-11-03T10:00:00+01:00. A time without a zone counts as Zurich time. length 3 to 40 |

## Examples

**curl**

```bash
curl -X POST "https://api.smartchat.marketing/v1/newsletters/nwl_3c9e1f7a5b2d4e8f9a0b1c2d3e4f5a6b/send" \
  -H "Authorization: Bearer $SMARTCHAT_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{
  "when": "now"
}'
```

**Python**

```python
import os
import uuid
import requests

response = requests.post(
    "https://api.smartchat.marketing/v1/newsletters/nwl_3c9e1f7a5b2d4e8f9a0b1c2d3e4f5a6b/send",
    headers={
        "Authorization": "Bearer " + os.environ["SMARTCHAT_API_KEY"],
        "Idempotency-Key": str(uuid.uuid4()),
    },
    json={
        "when": "now",
    },
)
response.raise_for_status()
print(response.json())
```

**TypeScript**

```typescript
const response = await fetch("https://api.smartchat.marketing/v1/newsletters/nwl_3c9e1f7a5b2d4e8f9a0b1c2d3e4f5a6b/send", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.SMARTCHAT_API_KEY}`,
    "Idempotency-Key": crypto.randomUUID(),
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "when": "now"
  }),
});
if (!response.ok) throw new Error(await response.text());
console.log(await response.json());
```

Response (202):


```json
{
  "object": "newsletter_send",
  "id": "nwl_3c9e1f7a5b2d4e8f9a0b1c2d3e4f5a6b",
  "newsletter_id": "nwl_3c9e1f7a5b2d4e8f9a0b1c2d3e4f5a6b",
  "status": "sending",
  "recipients": 412,
  "scheduled_at": null
}
```

## Response

Status 202. Every response has the headers `Request-Id`, `SmartChat-Version` and `X-RateLimit-*`.

| Name | Type | Description |
|---|---|---|
| `object` | string | Always "newsletter_send". always `newsletter_send` |
| `id` | string | ID of the send. It is the newsletter ID. |
| `newsletter_id` | string | Newsletter ID. |
| `status` | string | sending = messages are queued now. scheduled = they go out at scheduled_at. one of: `sending`, `scheduled` |
| `recipients` | integer | Contacts that receive the newsletter. 0 to 100000000 |
| `scheduled_at` | string or null | When the send starts if it is scheduled, otherwise null. up to 40 characters; format date-time |

## Errors

| Code | Status | When |
|---|---|---|
| [`bad_request`](https://docs.smartchat.marketing/en/errors/#bad_request) | 400 | The request could not be read. |
| [`idempotency_key_invalid`](https://docs.smartchat.marketing/en/errors/#idempotency_key_invalid) | 400 | The 'Idempotency-Key' header must be 1 to 255 visible ASCII characters. |
| [`idempotency_key_required`](https://docs.smartchat.marketing/en/errors/#idempotency_key_required) | 400 | This call needs an 'Idempotency-Key' header. |
| [`missing_parameter`](https://docs.smartchat.marketing/en/errors/#missing_parameter) | 400 | A required field is missing. |
| [`unknown_parameter`](https://docs.smartchat.marketing/en/errors/#unknown_parameter) | 400 | A field is not known. |
| [`api_key_expired`](https://docs.smartchat.marketing/en/errors/#api_key_expired) | 401 | This API key has expired. |
| [`api_key_invalid`](https://docs.smartchat.marketing/en/errors/#api_key_invalid) | 401 | This API key is not valid. |
| [`api_key_revoked`](https://docs.smartchat.marketing/en/errors/#api_key_revoked) | 401 | This API key was revoked. |
| [`authentication_required`](https://docs.smartchat.marketing/en/errors/#authentication_required) | 401 | No API key was sent. Send 'Authorization: Bearer <key>'. |
| [`insufficient_credits`](https://docs.smartchat.marketing/en/errors/#insufficient_credits) | 402 | The credits are not enough. |
| [`quota_exceeded`](https://docs.smartchat.marketing/en/errors/#quota_exceeded) | 402 | The monthly message quota is used up. |
| [`account_blocked`](https://docs.smartchat.marketing/en/errors/#account_blocked) | 403 | This account is blocked. |
| [`insufficient_scope`](https://docs.smartchat.marketing/en/errors/#insufficient_scope) | 403 | This key lacks a required permission. |
| [`ip_not_allowed`](https://docs.smartchat.marketing/en/errors/#ip_not_allowed) | 403 | This IP address is not allowed for this key. |
| [`subscription_locked`](https://docs.smartchat.marketing/en/errors/#subscription_locked) | 403 | The subscription or payment state blocks this function. |
| [`newsletter_not_found`](https://docs.smartchat.marketing/en/errors/#newsletter_not_found) | 404 | No newsletter with this ID exists in this account. |
| [`conflict`](https://docs.smartchat.marketing/en/errors/#conflict) | 409 | The state of the object does not allow this. |
| [`idempotency_in_progress`](https://docs.smartchat.marketing/en/errors/#idempotency_in_progress) | 409 | A request with this idempotency key is still running. |
| [`newsletter_locked`](https://docs.smartchat.marketing/en/errors/#newsletter_locked) | 409 | The newsletter is scheduled or sent and cannot be changed. |
| [`audience_empty`](https://docs.smartchat.marketing/en/errors/#audience_empty) | 422 | The audience has no reachable contacts. |
| [`idempotency_key_reused`](https://docs.smartchat.marketing/en/errors/#idempotency_key_reused) | 422 | This idempotency key was already used with a different request. |
| [`template_not_approved`](https://docs.smartchat.marketing/en/errors/#template_not_approved) | 422 | The template is not approved. |
| [`template_rejected`](https://docs.smartchat.marketing/en/errors/#template_rejected) | 422 | WhatsApp rejected the template. |
| [`validation_failed`](https://docs.smartchat.marketing/en/errors/#validation_failed) | 422 | A field is not valid. |
| [`whatsapp_not_connected`](https://docs.smartchat.marketing/en/errors/#whatsapp_not_connected) | 422 | No WhatsApp number is connected. |
| [`rate_limited`](https://docs.smartchat.marketing/en/errors/#rate_limited) | 429 | Too many requests. Wait and try again. |
| [`internal_error`](https://docs.smartchat.marketing/en/errors/#internal_error) | 500 | Something went wrong on our side. |
| [`upstream_error`](https://docs.smartchat.marketing/en/errors/#upstream_error) | 502 | A connected service (for example WhatsApp) reported an error. |
| [`service_unavailable`](https://docs.smartchat.marketing/en/errors/#service_unavailable) | 503 | The service is temporarily unavailable. |
| [`suppression_check_unavailable`](https://docs.smartchat.marketing/en/errors/#suppression_check_unavailable) | 503 | The suppression list cannot be read, so nothing was sent. |

All errors use [one format](https://docs.smartchat.marketing/en/concepts/errors-overview/).