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

# Add Thread Labels

> Apply one or more labels to a thread.

Labels already on the thread stay on it. If any label ID is not found, the
request returns a `404` and nothing changes. To replace the thread's labels
instead, use [Set Thread Labels](/docs/api-reference/inboxes/set-thread-labels).

## Path Parameters

The Inbox ID or the inbox email address, such as `support@example.com`.

The Thread ID.

## Body Parameters

**labels** `string[]` *required*

The IDs of the labels to apply. Between 1 and 10 IDs, each belonging to the
inbox.

## Response Fields

**object** `string`

Always `list`.

**data** `array`

Every label on the thread after the change.

**properties**

**id** `string`

The ID of the label.

**name** `string`

The name of the label.

**color** `string`

The color of the label as an uppercase `#RRGGBB` hex code, like
`#E93D82`.

```ts Node.js theme={"theme":{"light":"github-light","dark":"vesper"}}
import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

const { data, error } = await resend.inboxes.threads.labels.add({
  inboxId: 'b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1',
  threadId: '4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12',
  labels: ['7f9c1d2e-4a6b-4c3d-8e15-9b0a7c6d5e34'],
});
```

```php PHP theme={"theme":{"light":"github-light","dark":"vesper"}}
$resend = Resend::client('re_xxxxxxxxx');

$resend->inboxes->threads->labels->add(
  'b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1',
  '4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12',
  [
    'labels' => ['7f9c1d2e-4a6b-4c3d-8e15-9b0a7c6d5e34'],
  ]
);
```

```python Python theme={"theme":{"light":"github-light","dark":"vesper"}}
import resend

resend.api_key = "re_xxxxxxxxx"

params: resend.Inboxes.Threads.Labels.AddParams = {
    "inbox_id": "b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1",
    "thread_id": "4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12",
    "labels": ["7f9c1d2e-4a6b-4c3d-8e15-9b0a7c6d5e34"],
}

resend.Inboxes.Threads.Labels.add(params)
```

```ruby Ruby theme={"theme":{"light":"github-light","dark":"vesper"}}
require "resend"

Resend.api_key = "re_xxxxxxxxx"

params = {
  inbox_id: "b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1",
  thread_id: "4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12",
  labels: ["7f9c1d2e-4a6b-4c3d-8e15-9b0a7c6d5e34"]
}

Resend::Inboxes::Threads::Labels.add(params)
```

```go Go theme={"theme":{"light":"github-light","dark":"vesper"}}
package main

import "github.com/resend/resend-go/v4"

func main() {
	client := resend.NewClient("re_xxxxxxxxx")

	params := &resend.AddInboxThreadLabelsRequest{
		Labels: []string{"7f9c1d2e-4a6b-4c3d-8e15-9b0a7c6d5e34"},
	}

	client.Inboxes.Threads.Labels.Add(
		"b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1",
		"4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12",
		params,
	)
```

```rust Rust theme={"theme":{"light":"github-light","dark":"vesper"}}
use resend_rs::{Resend, Result};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let _labels = resend
    .inboxes
    .add_thread_labels(
      "b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1",
      "4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12",
      &["7f9c1d2e-4a6b-4c3d-8e15-9b0a7c6d5e34"],
    )
    .await?;

  Ok(())
}
```

```csharp .NET theme={"theme":{"light":"github-light","dark":"vesper"}}
using Resend;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" ); // Or from DI

var resp = await resend.InboxThreadLabelAddAsync(
    new Guid( "b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1" ),
    new Guid( "4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12" ),
    [ new Guid( "7f9c1d2e-4a6b-4c3d-8e15-9b0a7c6d5e34" ) ]
);
Console.WriteLine( "Nr Labels={0}", resp.Content.Count );
```

```bash cURL theme={"theme":{"light":"github-light","dark":"vesper"}}
curl -X POST 'https://api.resend.com/inboxes/b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1/threads/4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12/labels' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d $'{
  "labels": ["7f9c1d2e-4a6b-4c3d-8e15-9b0a7c6d5e34"]
}'
```

```bash CLI theme={"theme":{"light":"github-light","dark":"vesper"}}
resend inboxes threads labels add b3e2b2b6-3f0e-4c8e-9ad3-2f43a1e2c7f1 4d8e2a1c-9b3f-4c6d-8a21-3e5f7c9c0d12 \
  --labels 7f9c1d2e-4a6b-4c3d-8e15-9b0a7c6d5e34
```

```json Response theme={"theme":{"light":"github-light","dark":"vesper"}}
{
  "object": "list",
  "data": [
    {
      "id": "2a8b4c6d-1e3f-4a5b-9c7d-8e0f1a2b3c4d",
      "name": "Billing",
      "color": "#00A2C7"
    },
    {
      "id": "7f9c1d2e-4a6b-4c3d-8e15-9b0a7c6d5e34",
      "name": "Urgent",
      "color": "#E93D82"
    }
  ]
}
```