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

# TypeScript SDK

> Install and configure the Sendmux TypeScript SDK packages.

Use the TypeScript SDK when your application needs package-managed clients for one or more Sendmux API surfaces.

<Info>
  Sending clients accept a send-capable `smx_mbx_` key or owner-approved Sending-resource `smx_agent_` token. Mailbox clients accept
  `smx_mbx_` keys or scoped `smx_agent_` tokens. Management clients require
  team-scoped `smx_root_` keys.
</Info>

## Requirements

* A Sendmux API key for the surface you are calling.
* An application that can install packages from npm.

## Install

Install the umbrella package when one application needs more than one API surface.

<CodeGroup>
  ```bash Umbrella theme={null}
  npm install @sendmux/sdk
  ```

  ```bash Sending theme={null}
  npm install @sendmux/sending
  ```

  ```bash Mailbox theme={null}
  npm install @sendmux/mailbox
  ```

  ```bash Management theme={null}
  npm install @sendmux/management
  ```
</CodeGroup>

## Create a client

The umbrella package exports `sending`, `mailbox`, and `management` namespaces. Each namespace exposes the same factory as its surface package.

<CodeGroup>
  ```typescript Sending theme={null}
  import { sending } from "@sendmux/sdk";

  const client = sending.createSendingClient({
    apiKey: process.env.SENDMUX_MAILBOX_API_KEY!,
  });
  ```

  ```typescript Mailbox theme={null}
  import { mailbox } from "@sendmux/sdk";

  const client = mailbox.createMailboxClient({
    apiKey: process.env.SENDMUX_MAILBOX_API_KEY!,
  });
  ```

  ```typescript Management theme={null}
  import { management } from "@sendmux/sdk";

  const client = management.createManagementClient({
    apiKey: process.env.SENDMUX_ROOT_API_KEY!,
  });
  ```
</CodeGroup>

Surface packages expose `createSendingClient`, `createMailboxClient`, and `createManagementClient` directly.

## Choose a surface

| Surface    | Package               | Factory                  | API key                                                     |
| ---------- | --------------------- | ------------------------ | ----------------------------------------------------------- |
| Sending    | `@sendmux/sending`    | `createSendingClient`    | `smx_mbx_` or owner-approved `smx_agent_` with `email.send` |
| Mailbox    | `@sendmux/mailbox`    | `createMailboxClient`    | `smx_mbx_` or scoped `smx_agent_`                           |
| Management | `@sendmux/management` | `createManagementClient` | `smx_root_`                                                 |

<Note>
  Pre-claim `smx_agent_` tokens are mailbox-compatible only. Owner-approved Sending-resource `smx_agent_` tokens can send. Pre-claim self-registered agent tokens include `mailbox.read` and `email.receive`, not `email.send`.
</Note>

Sending uses `https://smtp.sendmux.ai/api/v1` by default. Mailbox and Management use `https://app.sendmux.ai/api/v1`.

## Shared API behaviour

The SDK configures bearer authentication, retries, and error mapping when you create a surface client.

### Pagination

List responses use cursor pagination with `pagination.has_more` and `pagination.next_cursor`. The core package exports `paginate()` for cursor iteration when you wrap a page-fetching function.

### Retries and rate limits

The default retry client retries safe methods and retry-safe `POST` requests that include `Idempotency-Key`. It honours `Retry-After` and `X-RateLimit-Reset` response headers.

Pass `retry` into a client factory to change `maxAttempts`, delay, replay body size, or jitter.

### Idempotency and ETags

Use core header helpers when a generated operation accepts custom headers.

```typescript theme={null}
import { core } from "@sendmux/sdk";

const retryHeaders = core.idempotencyHeaders("order-123");
const updateHeaders = core.conditionalHeaders({ ifMatch: etag });
const cacheHeaders = core.conditionalHeaders({ ifNoneMatch: etag });
```

Use `Idempotency-Key` for retry-safe mutating requests. Use `If-Match` and `If-None-Match` with single-resource endpoints that support ETags.

### Errors

Generated client errors are mapped to `SendmuxApiError`. The error exposes the API error code, retryability, request ID, response status, headers, and raw body when available.

Use `error.retryable` and `error.requestId` when deciding whether to retry or contact support.

## Next steps

<CardGroup cols={2}>
  <Card title="SDK overview" icon="code" href="/docs/sdks">
    Choose the right package family and API surface.
  </Card>

  <Card title="Versioning and support" icon="rotate" href="/docs/sdks/versioning-support">
    Check compatibility, support, and upgrade guidance.
  </Card>

  <Card title="Sending API" icon="paper-plane" href="/docs/sending-api/introduction">
    Review the Sending API contract used by `@sendmux/sending`.
  </Card>

  <Card title="API keys" icon="key" href="/docs/guides/api-keys">
    Create and scope the credentials used by SDK clients.
  </Card>
</CardGroup>