resend

Files (23)

• SKILL.md
• api-keys.md · references/
• automations.md · references/
• broadcasts.md · references/
• contact-properties.md · references/
• contacts.md · references/
• domains.md · references/
• events.md · references/
• fetch-all-templates.mjs · references/
• inboxes.md · references/
• installation.md · references/
• logs.md · references/
• receiving.md · references/
• segments.md · references/
• batch-email-examples.md · references/sending/
• best-practices.md · references/sending/
• email-management.md · references/sending/
• overview.md · references/sending/
• single-email-examples.md · references/sending/
• templates.md · references/
• topics.md · references/
• usage.md · references/
• webhooks.md · references/

SKILL.md (first lines)

# Resend

## Quick Send — Node.js

```typescript
import { Resend } from 'resend';

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

const { data, error } = await resend.emails.send(
  {
    from: 'Acme <onboarding@resend.dev>',
    to: ['delivered@resend.dev'],
    subject: 'Hello World',
    html: '<p>Email body here</p>',
  },
  { idempotencyKey: `welcome-email/${userId}` }
);

if (error) {
  console.error('Failed:', error.message);
  return;
}
console.log('Sent:', data.id);
```

**Key gotcha:** The Resend Node.js SDK does NOT throw exceptions — it returns `{ data, error }`. Always check `error` explicitly instead of using try/catch for API errors.

## Quick Send — Python

```python
import resend
import os

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

email = resend.Emails.send({
    "from": "Acme <onboarding@resend.dev>",
    "to": ["delivered@resend.dev"],
    "subject": "Hello World",
    "html": "<p>Email body here</p>",
}, idempotency_key=f"welcome-email/{user_id}")
```

### Single vs Batch Decision

| Choose | When |
|--------|------|
| **Single** (`POST /emails`) | 1 email, needs attachments, needs scheduling |
| **Batch** (`POST /emails/batch`) | 2-100 distinct emails, no attachments, no scheduling |

Batch is atomic — if one email fails validation, the entire batch fails. Always validate before sending. Batch does NOT support attachments or `scheduled_at`.

### Idempotency Keys (Critical for Retries)

Prevent duplicate emails when retrying failed requests:

| Key Facts | |
|-----------|---|
| **Format (single)** | `<event-type>/<entity-id>` (e.g., `welcome-email/user-123`) |
| **Format (batch)** | `batch-<event-type>/<batch-id>` (e.g., `batch-orders/batch-456`) |
| **Expiration** | 24 hours |
| **Max length** | 256 characters |
| **Same key + same payload** | Returns original response without resending |
| **Same key + different payload** | Returns 409 error |

## Quick Receive (Node.js)

```typescript
import { Resend } from 'resend';

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

export async function POST(req: Request) {
  const payload = await req.text(); // Must use raw text, not req.json()

  const event = resend.webhooks.verify({
    payload,
    headers: {
      'svix-id': req.headers.get('svix-id'),
      'svix-timestamp': req.headers.get('svix-timestamp'),
      'svix-signature': req.headers.get('svix-signature'),
    },
    secret: process.env.RESEND_WEBHOOK_SECRET,
  });

  if (event.type === 'email.received') {
    // Webhook has metadata only — call API for body
    const { data: email } = await resend.emails.receiving.get(
      event.data.email_id
    );
    console.log(email.text);
  }

  return new Response('OK', { status: 200 });
}
```

**Key gotcha:** Webhook payloads do NOT contain the email body. You must call `resend.emails.receiving.get()` separately.

## What Do You Need?

| Task | Reference |
|------|-----------|
| **Send a single email** | [sending/overview.md](references/sending/overview.md) — parameters, deliverability, testing |
| **Send batch emails** | [sending/overview.md](references/sending/overview.md) → [sending/batch-email-examples.md](references/sending/batch-email-examples.md) |
| **Full SDK examples** (Node.js, Python, Go, cURL) | [sending/single-email-examples.md](references/sending/single-email-examples.md) |
| **Idempotency, retries, error handling** | [sending/best-practices.md](references/sending/best-practices.md) |
| **Get, list, reschedule, cancel emails, retrieve metrics** | [sending/email-management.md](references/sending/email-management.md) |
| **Receive inbound emails** | [receiving.md](references/receiving.md) — domain setup, webhooks, attachments |
| **Manage templates** (CRUD, variables) | [templates.md](references/templates.md) — lifecycle, aliases, pagination |
| **Set up webhooks** (events, verification) | [webhooks.md](references/webhooks.md) — verification, CRUD, retry schedule, IP allowlist |
| **Manage domains** (create, verify, claim, DNS) | [domains.md](references/domains.md) — regions, TLS, tracking, claiming, capabilities |
| **Manage contacts** (CRUD, properties) | [contacts.md](references/contacts.md) — segments, topics, custom properties, bulk CSV import |
| **Send broadcasts** (marketing campaigns) | [broadcasts.md](references/broadcasts.md) — lifecycle, scheduling, template variables |
| **Manage API keys** | [api-keys.md](references/api-keys.md) — permission scoping, domain restrictions |
| **View API request logs** | [logs.md](references/logs.md) — list and retrieve API call history, debugging |
| **Define contact properties** | [contact-properties.md](references/contact-properties.md) — custom fields for contacts |
| **Manage segments** (contact groups) | [segments.md](references/segments.md) — broadcast targeting, contact grouping |

From resend/resend-skills, MIT.

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