> ## 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.

# Python SDK

> Install and configure the Sendmux Python SDK packages.

Use the Python SDK when your application needs Sendmux API clients with API-key validation, retry handling, cursor helpers, and typed API errors.

<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

* Python 3.10 or newer.
* A Sendmux API key for the surface you are calling.

## Install

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

<CodeGroup>
  ```bash Umbrella theme={null}
  pip install sendmux-sdk
  ```

  ```bash Sending theme={null}
  pip install sendmux-sending
  ```

  ```bash Mailbox theme={null}
  pip install sendmux-mailbox
  ```

  ```bash Management theme={null}
  pip install sendmux-management
  ```
</CodeGroup>

## Create a client

The umbrella package lazy-loads `sending`, `mailbox`, and `management` modules.

<CodeGroup>
  ```python Sending theme={null}
  import os
  from sendmux_sdk import sending

  client = sending.create_sending_client(
      api_key=os.environ["SENDMUX_MAILBOX_API_KEY"],
  )
  ```

  ```python Mailbox theme={null}
  import os
  from sendmux_sdk import mailbox

  client = mailbox.create_mailbox_client(
      api_key=os.environ["SENDMUX_MAILBOX_API_KEY"],
  )
  ```

  ```python Management theme={null}
  import os
  from sendmux_sdk import management

  client = management.create_management_client(
      api_key=os.environ["SENDMUX_ROOT_API_KEY"],
  )
  ```
</CodeGroup>

Surface packages expose `create_sending_client`, `create_mailbox_client`, and `create_management_client` directly.

## Choose a surface

| Surface    | Package              | Factory                    | API key                                                     |
| ---------- | -------------------- | -------------------------- | ----------------------------------------------------------- |
| Sending    | `sendmux-sending`    | `create_sending_client`    | `smx_mbx_` or owner-approved `smx_agent_` with `email.send` |
| Mailbox    | `sendmux-mailbox`    | `create_mailbox_client`    | `smx_mbx_` or scoped `smx_agent_`                           |
| Management | `sendmux-management` | `create_management_client` | `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 surface factories validate API key prefixes, attach bearer auth, and wrap generated API errors.

### Pagination

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

### Retries and rate limits

Surface clients use a retrying request client. It retries safe methods and retry-safe `POST` requests that include `Idempotency-Key`, then honours `Retry-After` and `X-RateLimit-Reset` response headers.

Pass `RetryOptions` into a client factory to change attempts, delays, or sleep behaviour.

### Idempotency and ETags

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

```python theme={null}
from sendmux_core import conditional_headers, idempotency_headers

headers = {
    **idempotency_headers("order-123"),
    **conditional_headers(if_match=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 exceptions are mapped to `SendmuxApiError`. The error carries the API error code, retryability, request ID, status, headers, and raw body when available.

Use `error.retryable` and `error.request_id` 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="Mailbox API" icon="inbox" href="/docs/mailbox-api/introduction">
    Review the Mailbox API contract used by `sendmux-mailbox`.
  </Card>

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