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

# AI onboarding

> Everything you need to onboard your AI agent to Resend.

If you're developing with AI, Resend offers several resources to improve your experience.

* [Resend MCP Server](#resend-mcp-server)
* [Resend CLI](#resend-cli)
* [Resend Docs for Agents](#resend-docs-for-agents)
* [Email Skills for Agents](#email-skills-for-agents)
* [Quick Start Guides](#quick-start-guides)
* [OpenClaw Guide](#openclaw-guide)
* [Chat SDK](#chat-sdk)
* [AI Builder Guides](#ai-builder-guides)
* [AI Integrations](#ai-integrations)

## Prerequisite: Create an API Key

A human must create the Resend account. Once you have an account, you'll need to [create an API key](/docs/create-an-api-key). With an API key, your agent can perform many other tasks.

> [!NOTE]
>
> To send or receive with Resend, you'll need to [verify a domain](https://resend.com/domains). While an agent can [create a domain](/docs/api-reference/domains/create-domain), the API returns DNS records you will need to add in your DNS provider before [verifying your DNS records](/docs/api-reference/domains/verify-domain). You may find it easier to verify your domain in the dashboard.

## Resend MCP Server

MCP is an open protocol that standardizes how applications provide context to LLMs. Among other benefits, it provides LLMs tools to act on your behalf. Our [MCP server](https://github.com/resend/resend-mcp) is open-source and covers our full API surface area.

Resend hosts the MCP server, so you can connect any MCP client without installing anything:

```
https://mcp.resend.com/mcp
```

When you connect, your client authenticates with OAuth by opening a browser to log in to Resend. Clients that can't complete a browser login can pass an API key as a Bearer token instead. You can also run the server locally with `npx` using the `resend-mcp` package on NPM.

The [Resend plugin](https://github.com/resend/resend-skills) follows the [Agent Plugins](https://agent-plugins.org) spec. On clients whose landing page installs that plugin, it adds the remote MCP server and the Resend skills together. Setup for each client is on the [MCP server page](/docs/mcp-server), and it matches the page at resend.com. Claude and Codex also keep these one-click installs:

* [Resend connector for Claude](https://claude.ai/directory/connectors/resend)
* [Resend plugin for Codex](https://chatgpt.com/plugins/plugin_asdk_app_6a3c407853888191beddc2151c2b6f8b?open_in_codex)

> **[MCP Server](/docs/mcp-server)**
>
> View setup instructions for Claude, Cursor, Codex, Copilot, Hermes, OpenClaw,
> and more.

## Resend CLI

The Resend CLI lets you send emails, manage your account, and develop locally, all from the terminal. It's built for humans, AI agents, and CI/CD pipelines.

```bash theme={"theme":{"light":"github-light","dark":"vesper"}}
# Authenticate
resend login

# Send an email
resend emails send \
  --from "you@example.com" \
  --to hello@example.com \
  --subject "Hello" \
  --text "Sent from my terminal."
```

The CLI also includes a full local webhook setup for developing with inbound email events without deploying anything.

> **[Resend CLI](/docs/cli)**
>
> Install the CLI and set up a local webhook development environment.

## Resend Docs for Agents

You can give your agent current docs in a context-aware way in three ways:

1. **Markdown docs**

   Every doc includes a markdown version (append `md` to any page)

   ```
   Docs for this page: https://resend.com/docs/ai-onboarding.md
   ```

2. **Full llms.txt**

   Give your agent all our docs in a single file.

   ```
   Here are the Resend docs: https://resend.com/docs/llms-full.txt
   ```

3. **MCP Docs server**

   For a more structured approach using MCP tools, you can install our MCP docs server in any MCP client, like Cursor, Codex, or Claude Code.

   ```
   npx add-mcp https://resend.com/docs/mcp
   ```

## Email Skills for Agents

Skills give AI agents specialized knowledge for specific tasks.

Install skills with a single command:

```bash theme={"theme":{"light":"github-light","dark":"vesper"}}
npx skills add resend/resend-skills
```

Or install individually:

| Skill | Install | What it does |
| - | - | - |
| [Resend](/docs/resend-skill) | `npx skills add resend/resend-skills` | Send and receive emails, handle errors, and prevent duplicate sends. Get code examples from various SDKs. |
| [React Email](/docs/react-email-skill) | `npx skills add resend/react-email` | Build emails in React, Tailwind, and TypeScript. Audit existing React emails for style and cross-client rendering. |
| [Email Best Practices](/docs/email-best-practices-skill) | `npx skills add resend/email-best-practices` | Audit SPF/DKIM/DMARC setup, compliance (CAN-SPAM, GDPR), webhook handling |

## Quick Start Guides

The documentation includes quick start guides for common tasks with Resend. They contain step-by-step instructions for sending emails, creating templates, and more. Copy the prompt for your agent or click to open in Cursor.

Resend provides two endpoints for sending emails:

| Approach | Endpoint | Use Case |
| - | - | - |
| **Single** | `POST /emails` | Individual transactional emails, emails with attachments, scheduled sends |
| **Batch** | `POST /emails/batch` | Multiple distinct emails in one request (max 100), bulk notifications |

**Choose batch when:**

* Sending 2+ distinct emails at once
* Reducing API calls is important (by default, rate limit is 10 requests per second)
* No attachments or scheduling needed

**Choose single when:**

* Sending one email
* Email needs attachments
* Email needs to be scheduled
* Different recipients need different timing

## Quick Start

1. **Detect project language** from config files (package.json, requirements.txt, go.mod, etc.)
2. **Install SDK** (preferred) or use cURL
3. **Choose single or batch** based on the decision matrix above
4. **Implement best practices** - Idempotency keys, error handling, retries

## Best Practices (Critical for Production)

Always implement these for production email sending.

### Idempotency Keys

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 |
| **Duplicate payload** | Returns original response without resending |
| **Different payload** | Returns 409 error |

### Error Handling

| Code | Action |
| - | - |
| 400, 422 | Fix request parameters, don't retry |
| 401, 403 | Check API key / verify domain, don't retry |
| 409 | Idempotency conflict - use new key or fix payload |
| 429 | Rate limited - retry with exponential backoff (by default, rate limit is 10 requests/second) |
| 500 | Server error - retry with exponential backoff |

### Retry Strategy

* **Backoff:** Exponential (1s, 2s, 4s...)
* **Max retries:** 3-5 for most use cases
* **Only retry:** 429 (rate limit) and 500 (server error)
* **Always use:** Idempotency keys when retrying

## Single Email

**Endpoint:** `POST /emails` (prefer SDK over cURL)

### Required Parameters

| Parameter | Type | Description |
| - | - | - |
| `from` | string | Sender address. Format: `"Name <email@domain.com>"` |
| `to` | string\[] | Recipient addresses (max 50) |
| `subject` | string | Email subject line |
| `html` or `text` | string | Email body content |

### Optional Parameters

| Parameter | Type | Description |
| - | - | - |
| `cc` | string\[] | CC recipients |
| `bcc` | string\[] | BCC recipients |
| `reply_to`\* | string\[] | Reply-to addresses |
| `scheduled_at`\* | string | Schedule send time (ISO 8601) |
| `attachments` | array | File attachments (max 40MB total) |
| `tags` | array | Key/value pairs for tracking |
| `headers` | object | Custom headers |

\*Parameter naming varies by SDK (e.g., `replyTo` in Node.js, `reply_to` in Python).

### Minimal Example (Node.js)

```typescript theme={"theme":{"light":"github-light","dark":"vesper"}}
import { Resend } from 'resend';

const resend = new Resend('YOUR_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);
```

## Batch Email

**Endpoint:** `POST /emails/batch` (but prefer SDK over cURL)

### Limitations

* **No attachments** - Use single sends for emails with attachments
* **No scheduling** - Use single sends for scheduled emails
* **Atomic** - If one email fails validation, the entire batch fails
* **Max 100 emails** per request
* **Max 50 recipients** per individual email in the batch

### Pre-validation

Since the entire batch fails on any validation error, validate all emails before sending:

* Check required fields (from, to, subject, html/text)
* Validate email formats
* Ensure batch size is less than or equal to 100

### Minimal Example (Node.js)

```typescript theme={"theme":{"light":"github-light","dark":"vesper"}}
import { Resend } from 'resend';

const resend = new Resend('YOUR_RESEND_API_KEY');

const { data, error } = await resend.batch.send(
  [
    {
      from: 'Acme <hello@example.com>',
      to: ['delivered@resend.dev'],
      subject: 'Order Shipped',
      html: '<p>Your order has shipped!</p>',
    },
    {
      from: 'Acme <hello@example.com>',
      to: ['delivered@resend.dev'],
      subject: 'Order Confirmed',
      html: '<p>Your order is confirmed!</p>',
    },
  ],
  { idempotencyKey: `batch-orders/${batchId}` },
);

if (error) {
  console.error('Batch failed:', error.message);
  return;
}
console.log(
  'Sent:',
  data.map((e) => e.id),
);
```

## OpenClaw Guide

Equipping your agent with its own email inbox can be a powerful tool to unlock new workflows. Alternatively, give it access to your Resend account to support agentic flows for sending and receiving emails.

> **[Email Automation for OpenClaw using Resend](/docs/openclaw-guide)**
>
> View the OpenClaw guide.

## Chat SDK

The `@resend/chat-sdk-adapter` package is a Vercel Chat SDK adapter that turns email into a two-way communication channel. Receive inbound emails through webhooks, reply through the Resend API, and let the adapter handle threading automatically. It also supports card emails, attachments, and proactive outreach.

> **[Chat SDK](/docs/chat-sdk)**
>
> Build conversational email experiences with the Chat SDK adapter.

## AI Builder Guides

Get started using Resend with popular AI builders:

* [Anything Integration](/docs/anything-integration)
* [Lovable Integration](/docs/lovable-integration)
* [v0 Integration](/docs/v0-integration)
* [Bolt.new Integration](/docs/bolt-new-integration)
* [Replit Integration](/docs/replit-integration)
* [Base44 Integration](/docs/base44-integration)
* [Leap.new Integration](/docs/leap-new-integration)

## AI Integrations

Several AI tools have created integrations for working with Resend. Visit their documentation for information on integrating Resend with their tools.

> **[Lovable](https://docs.lovable.dev/integrations/resend)**
>
> Tell the Lovable AI to send emails

> **[Anything](https://www.createanything.com/docs/integrations/resend)**
>
> Add email to your Anything projects

> **[Wildcard](https://github.com/wild-card-ai/agents-json/blob/master/examples/resend.ipynb)**
>
> Send natural language emails using Wildcard

> **[mcp.run](https://www.mcp.run/nilslice/resend)**
>
> Build email AI agents using mcp.run

> **[Rocket](https://docs.rocket.new/integrations/resend)**
>
> Send emails from apps built with Rocket

> **[Base44](https://docs.base44.com/Integrations/Resend-integration)**
>
> Add email to your Base44 apps

> **[Leap.new](https://docs.leap.new/integrations/resend)**
>
> Add email to your Leap apps

> **[Parsley](https://www.parsley.id/integrations/resend)**
>
> Send alerts and follow-ups with Parsley

> **[Pica](https://www.picaos.com/integrations/resend)**
>
> Integrate Pica with Resend