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

# Resend

> The Resend mirror — transactional email, webhook events with Svix-style HMAC signing, domains and audiences.

Target vendor: [Resend API](https://resend.com/docs/api-reference). Webhook signing: Svix-style HMAC-SHA256 (`svix-id`, `svix-timestamp`, `svix-signature` headers).

## Mirror URL

```
https://resend-<session_id>.mirra.run
```

Example: `https://resend-a7k2.mirra.run`.

## SDK compatibility

Official Resend SDKs work against the mirror with zero code changes when routed via the TLS proxy:

<Tabs>
  <Tab title="Node">
    ```typescript theme={null}
    import { Resend } from 'resend';

    const resend = new Resend(process.env.RESEND_API_KEY);

    const { id } = await resend.emails.send({
      from: 'hello@mail.acme.com',
      to: 'alice@test.com',
      subject: 'Welcome',
      html: '<p>Welcome to Acme.</p>',
    });
    // → routed to resend-a7k2.mirra.run
    ```
  </Tab>

  <Tab title="Python">
    ```python theme={null}
    import resend

    resend.api_key = os.environ['RESEND_API_KEY']

    resend.Emails.send({
      'from': 'hello@mail.acme.com',
      'to': 'alice@test.com',
      'subject': 'Welcome',
      'html': '<p>Welcome to Acme.</p>',
    })
    # → routed to resend-a7k2.mirra.run
    ```
  </Tab>

  <Tab title="Without the TLS proxy">
    ```typescript theme={null}
    import { Resend } from 'resend';

    const resend = new Resend(process.env.RESEND_API_KEY, {
      baseUrl: 'https://resend-a7k2.mirra.run',
    });
    ```
  </Tab>
</Tabs>

## Supported surface

### Resources

<AccordionGroup>
  <Accordion title="Emails">
    Send single emails, batch-send, retrieve by ID, list. HTML + plain text bodies, attachments, tags, reply-to, cc/bcc.
  </Accordion>

  <Accordion title="Domains">
    Create, verify, retrieve, list, delete. Verification status transitions (`pending → verified` / `failed`). DNS record generation.
  </Accordion>

  <Accordion title="API Keys">
    Create, list, revoke. Name, scope, permission levels. Last-used tracking.
  </Accordion>

  <Accordion title="Audiences & Contacts">
    Audience CRUD. Contact add, update, unsubscribe, delete. Bulk import.
  </Accordion>

  <Accordion title="Broadcasts">
    Create, schedule, send, list. Audience targeting. Preview.
  </Accordion>
</AccordionGroup>

### Webhooks

All Resend webhook event types fire with vendor-correct Svix-style signatures:

* `email.sent` — immediately after a successful send
* `email.delivered` — a few seconds after send (configurable per fixture)
* `email.delivery_delayed` — when delivery is delayed by downstream providers
* `email.bounced` — hard and soft bounces
* `email.complained` — spam complaints
* `email.opened` — tracking pixel hit
* `email.clicked` — link click

Signing headers:

```
svix-id:        msg_28pxRt9jRYvJMq8yc6ZD
svix-timestamp: 1713802534
svix-signature: v1,g0hM9SsE+OTPJTGt/tmIKtSyZlE3uFJELVlNIOLJ1OE=
```

Verify using the official Resend webhooks library, no code changes:

```typescript theme={null}
import { Webhook } from 'svix';

const wh = new Webhook(process.env.RESEND_WEBHOOK_SECRET);
const event = wh.verify(rawBody, {
  'svix-id':        req.headers['svix-id'],
  'svix-timestamp': req.headers['svix-timestamp'],
  'svix-signature': req.headers['svix-signature'],
});
```

## Built-in fixtures

<AccordionGroup>
  <Accordion title="resend:empty">
    No domains, no emails. A blank Resend account.
  </Accordion>

  <Accordion title="resend:transactional-busy">
    One verified domain `mail.acme.com`, 100 sent emails across the last 7 days with realistic delivery/bounce/open rates. Good for testing scale behavior.
  </Accordion>

  <Accordion title="resend:bounced-domain">
    Domain with recent bounce rate above the provider's threshold — suspended state. Good for testing your handler's response to `email.bounced` and domain suspension.
  </Accordion>

  <Accordion title="resend:marketing-list">
    Audience with 1,000 contacts and three prior broadcasts. Good for testing broadcast flows.
  </Accordion>

  <Accordion title="resend:over-quota">
    Account at monthly send limit. Any `POST /emails` returns `429` with Resend's exact rate-limit payload. Good for testing your quota-exceeded handling.
  </Accordion>
</AccordionGroup>

Load a fixture:

```bash theme={null}
mirra up --mirrors=resend --seed=resend:transactional-busy
```

## Coverage gaps

* **Suppression lists** — not yet mirrored.
* **Custom domains with CNAME proxies** — mocked as always-valid.
* **Open/click tracking pixels** — simulated via `/_mirra/simulate`, not from real client requests.

See [status.mirra.run/resend](https://status.mirra.run/resend) for the live list.

## Simulating events

Real delivery timing (a few seconds between `email.sent` and `email.delivered`) is simulated by the engine's event-dispatch scheduler — you get realistic timing without waiting on actual SMTP.

To force an immediate bounce or complaint for testing:

```bash theme={null}
curl -X POST https://resend-a7k2.mirra.run/_mirra/simulate \
  -H "Content-Type: application/json" \
  -d '{ "event": "email.bounced", "emailId": "email_abc", "bounce": { "type": "hard", "reason": "user not found" } }'
```

See [API reference](/reference/api#simulate) for the full event list.

## Where to go next

<Columns cols={2}>
  <Card title="Twilio" icon="message" href="/mirrors/twilio">
    The SMS mirror.
  </Card>

  <Card title="Stripe" icon="credit-card" href="/mirrors/stripe">
    The payments mirror.
  </Card>

  <Card title="First scenario" icon="file-lines" href="/guides/first-scenario">
    Write and run a Resend scenario end-to-end.
  </Card>
</Columns>