# Send emails with Django

> Use the PostShiba EmailBackend and django.core.mail.

## What you'll build

A Django email backend that sends through the PostShiba API. `send_mail`, `EmailMessage`, and `EmailMultiAlternatives` all use it once it is set.

## Before you start

- An API key with **Send only** access. **Full access** also works. See [Create an API key](/docs/create-an-api-key). Support keys cannot send.
- A verified sending domain. See [Add and verify a domain](/docs/add-a-domain). `from_email` must be an address on it.
- A cluster that is ready to send (`sending_ready` is `true`). See [Clusters](/docs/dashboard/clusters/introduction).
- Python 3.8 or later.

## Install

The package is on GitHub, not PyPI. Install it with the `django` extra.

```sh install.sh
pip install "postshiba[django] @ git+https://github.com/postshiba/postshiba-python.git"
```

## Send your first email

1. Set the backend and your API key in `settings.py`.

```python settings.py
EMAIL_BACKEND = "postshiba.django.EmailBackend"
POSTSHIBA_API_KEY = "YOUR_API_KEY"
```

2. Build a message with text and HTML, then call `send()`.

```python send.py
from django.core.mail import EmailMultiAlternatives

message = EmailMultiAlternatives(
    subject="Your receipt",
    body="Thanks for your order.",
    from_email="hello@mail.example.com",
    to=["you@example.com"],
    reply_to=["support@example.com"],
    headers={"X-Capsule-Unique-Args": '{"order_id": "ord_123"}'},
)
message.attach_alternative("<p>Thanks for your order.</p>", "text/html")
message.send()
```

Try it in `python manage.py shell`. `send()` returns `1` when the message is queued. The message then shows under Events in the dashboard.

The backend sends `X-Capsule-Unique-Args` as `unique_args` and other custom headers as `headers`. It always uses your first cluster that is ready to send.

## Attachments and templates

### Attach a file

Use Django's `attach` or `attach_file`. The backend base64-encodes each file for the API. Up to 10 files, 18 MB in total. See [Attachments](/docs/dashboard/emails/attachments) for allowed types.

```python attachment.py
from django.core.mail import EmailMessage

message = EmailMessage(
    subject="Your invoice",
    body="Your invoice is attached.",
    from_email="hello@mail.example.com",
    to=["you@example.com"],
)
message.attach_file("invoice.pdf")
message.send()
```

Django templates work as usual for the body. Hosted PostShiba templates go through the [Python client](/docs/send-with-python) with `template`, not through the backend.

## Keep the key safe

Use a **Send only** key in your app. It can send email and call `GET /api/v1/users/me`. Every other request returns `403` `forbidden`.

| If this key leaks | Send only | Full access |
| --- | --- | --- |
| Send mail from your verified domains | Yes | Yes |
| Read events, recipients, templates, and sent messages | No | Yes |
| See SMTP passwords and webhook secrets | No | Yes |
| Change clusters, domains, credentials, webhooks, and suppressions | No | Yes |

- Keep Full access keys for setup scripts, the [CLI](/docs/send-with-cli), and [MCP](/docs/connect-mcp). Don't deploy one with your app.
- Read the key from an environment variable in `settings.py`, such as `POSTSHIBA_API_KEY = os.environ["POSTSHIBA_API_KEY"]`. Don't commit it, log it, or put it in a URL.
- Send from your server. Never put a key, even a Send only key, in a template, browser code, or mobile code.
- Create one key per app and environment. If a key leaks, delete it on **API keys** and create a new one. Deleting stops it straight away.

## Troubleshooting

A failed send raises `postshiba.Error` with `error`, `field`, and `message`, unless you pass `fail_silently=True`.

| Status | `error` | What to do |
| --- | --- | --- |
| `401` | `Invalid token or no user signed in` | The API key is missing, mistyped, or deleted. Check `POSTSHIBA_API_KEY`. |
| `403` | `forbidden` | Support keys cannot send. Use a Send only or Full access key. A Send only key gets this on any call other than sending. |
| `403` | `domain_unverified` | `from_email` is not on a verified domain. |
| `403` | `kyc_required` | Your team is pending production approval. Until then, send only to team members, live inbox addresses, and inbox forward-to addresses. |
| `422` | `invalid` | `field` names the problem, such as a missing `to` or a rejected attachment. |
| `429` | `throttled` | The cluster hit its hourly throttle or 24-hour cap. Retrying right away hits the same cap. See [What happens at your cap](/docs/dashboard/clusters/what-happens-at-your-cap). |
| `429` | `rate_limited` | More than 300 send requests in one minute on one API key. Slow down. |

Every other status is on [Errors](/docs/api-reference/errors).

## Next steps

- [Send emails with Python](/docs/send-with-python) for the plain client.
- [Unique args](/docs/dashboard/emails/unique-args) to get your own ids back on delivery webhooks.
- [Managing webhooks](/docs/webhooks/introduction) to receive delivery events.
- [SDKs](/docs/sdks) for every language client.