# Send a batch

> POST /emails/batch — send up to 100 emails in one request.

`POST /emails/batch`

Send up to 100 emails in a single request. The body is a JSON **array** of email objects, each with the same shape as a [single send](https://www.mailblastr.com/docs/api/emails-send). Every item is validated before any email is sent; if one fails validation, the whole batch is rejected and nothing is sent. See [Batch sending](https://www.mailblastr.com/docs/emails/batch).

## Body

| Name | Type | Required | Description |
| --- | --- | --- | --- |
| `(array)` | object[] | Yes | An array of 1–100 email objects. Each object accepts the same fields as `POST /emails` (`from`, `to`, `subject`, `html`/`text`, `cc`, `bcc`, `reply_to`, `headers`, `tags`, `topic_id`, `template`). |

> **Warning:** The `attachments` and `scheduled_at` fields are **not supported** on the batch endpoint. An optional `Idempotency-Key` header (max 256 characters, expires after 24 hours) applies to the whole batch.

## Request

**Node.js**

```js
import { MailBlastr } from 'mailblastr';

const mb = new MailBlastr('mb_xxxxxxxxx');

const { data, error } = await mb.batch.send([
  { "from": "Acme <hello@yourdomain.com>", "to": ["a@example.com"], "subject": "Hi A", "html": "<p>Hello A</p>" },
  { "from": "Acme <hello@yourdomain.com>", "to": ["b@example.com"], "subject": "Hi B", "html": "<p>Hello B</p>" }
]);
console.log({ data, error });
```

**Ruby**

```ruby
require "mailblastr"

Mailblastr.api_key = "mb_xxxxxxxxx"

Mailblastr::Batch.send([
  {
    "from": "Acme <hello@yourdomain.com>",
    "to": [
      "a@example.com"
    ],
    "subject": "Hi A",
    "html": "<p>Hello A</p>"
  },
  {
    "from": "Acme <hello@yourdomain.com>",
    "to": [
      "b@example.com"
    ],
    "subject": "Hi B",
    "html": "<p>Hello B</p>"
  }
])
```

**PHP**

```php
$mailblastr = Mailblastr::client('mb_xxxxxxxxx');

$mailblastr->batch->send([
  [
    'from' => "Acme <hello@yourdomain.com>",
    'to' => [
      "a@example.com"
    ],
    'subject' => "Hi A",
    'html' => "<p>Hello A</p>"
  ],
  [
    'from' => "Acme <hello@yourdomain.com>",
    'to' => [
      "b@example.com"
    ],
    'subject' => "Hi B",
    'html' => "<p>Hello B</p>"
  ]
]);
```

**Python**

```python
import mailblastr

mailblastr.api_key = "mb_xxxxxxxxx"

mailblastr.Batch.send([
  {
    "from": "Acme <hello@yourdomain.com>",
    "to": [
      "a@example.com"
    ],
    "subject": "Hi A",
    "html": "<p>Hello A</p>"
  },
  {
    "from": "Acme <hello@yourdomain.com>",
    "to": [
      "b@example.com"
    ],
    "subject": "Hi B",
    "html": "<p>Hello B</p>"
  }
])
```

**Go**

```go
package main

import (
    "fmt"
    "io"
    "net/http"
    "strings"
)

func main() {
    req, _ := http.NewRequest("POST", "https://api.mailblastr.com/emails/batch", strings.NewReader(`[
  { "from": "Acme <hello@yourdomain.com>", "to": ["a@example.com"], "subject": "Hi A", "html": "<p>Hello A</p>" },
  { "from": "Acme <hello@yourdomain.com>", "to": ["b@example.com"], "subject": "Hi B", "html": "<p>Hello B</p>" }
]`))
    req.Header.Set("Authorization", "Bearer mb_xxxxxxxxx")
    req.Header.Set("Content-Type", "application/json")
    res, _ := http.DefaultClient.Do(req)
    defer res.Body.Close()
    out, _ := io.ReadAll(res.Body)
    fmt.Println(string(out))
}
```

**Rust**

```rust
use reqwest::Client;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let res = Client::new()
        .post("https://api.mailblastr.com/emails/batch")
        .header("Authorization", "Bearer mb_xxxxxxxxx")
        .header("Content-Type", "application/json")
        .body(r#"[
  { "from": "Acme <hello@yourdomain.com>", "to": ["a@example.com"], "subject": "Hi A", "html": "<p>Hello A</p>" },
  { "from": "Acme <hello@yourdomain.com>", "to": ["b@example.com"], "subject": "Hi B", "html": "<p>Hello B</p>" }
]"#)
        .send()
        .await?;
    println!("{}", res.text().await?);
    Ok(())
}
```

**Java**

```java
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

var client = HttpClient.newHttpClient();
var request = HttpRequest.newBuilder()
    .uri(URI.create("https://api.mailblastr.com/emails/batch"))
    .header("Authorization", "Bearer mb_xxxxxxxxx")
    .header("Content-Type", "application/json")
    .method("POST", HttpRequest.BodyPublishers.ofString("""
[
  { "from": "Acme <hello@yourdomain.com>", "to": ["a@example.com"], "subject": "Hi A", "html": "<p>Hello A</p>" },
  { "from": "Acme <hello@yourdomain.com>", "to": ["b@example.com"], "subject": "Hi B", "html": "<p>Hello B</p>" }
]
"""))
    .build();
var response = client.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println(response.body());
```

**.NET**

```csharp
using System.Net.Http;
using System.Text;

var client = new HttpClient();
var request = new HttpRequestMessage(HttpMethod.Post, "https://api.mailblastr.com/emails/batch");
request.Headers.Add("Authorization", "Bearer mb_xxxxxxxxx");
request.Content = new StringContent(@"[
  { ""from"": ""Acme <hello@yourdomain.com>"", ""to"": [""a@example.com""], ""subject"": ""Hi A"", ""html"": ""<p>Hello A</p>"" },
  { ""from"": ""Acme <hello@yourdomain.com>"", ""to"": [""b@example.com""], ""subject"": ""Hi B"", ""html"": ""<p>Hello B</p>"" }
]", Encoding.UTF8, "application/json");
var response = await client.SendAsync(request);
Console.WriteLine(await response.Content.ReadAsStringAsync());
```

**cURL**

```bash
curl -X POST 'https://api.mailblastr.com/emails/batch' \
  -H 'Authorization: Bearer mb_xxxxxxxxx' \
  -H 'Content-Type: application/json' \
  -d '[
  { "from": "Acme <hello@yourdomain.com>", "to": ["a@example.com"], "subject": "Hi A", "html": "<p>Hello A</p>" },
  { "from": "Acme <hello@yourdomain.com>", "to": ["b@example.com"], "subject": "Hi B", "html": "<p>Hello B</p>" }
]'
```

**CLI**

```bash
mailblastr emails batch \
  --data '[{"from":"Acme <hello@yourdomain.com>","to":["a@example.com"],"subject":"Hi A","html":"<p>Hello A</p>"},{"from":"Acme <hello@yourdomain.com>","to":["b@example.com"],"subject":"Hi B","html":"<p>Hello B</p>"}]'
```

## Response

A `data` array of created emails, in request order.

```json
{
  "data": [
    { "id": "49a3999c-0ce1-4ea6-ab68-afcd6dc2e794" },
    { "id": "1b2c3d4e-5f60-7a8b-9c0d-1e2f3a4b5c6d" }
  ]
}
```

## Errors

Returns `validation_error` if the body is not a non-empty array, if it contains more than 100 emails, or if any item fails validation (the failing item's error is returned and nothing is sent). See the [error reference](https://www.mailblastr.com/docs/api/errors).