<!-- https://headless-lms.dev/docs/adapters/email/resend -->

# Resend

Send transactional email through Resend with the email-resend adapter.

`@headless-lms/adapter-email-resend` implements the `EmailSender` port with [Resend](https://resend.com). The server hands it fully rendered emails (subject, HTML, plain text) — rendering is the [templates adapter's](/docs/adapters/email/react-email) job.

## Setup

1. Create a [Resend](https://resend.com) account and an API key.
2. Verify your sending domain in Resend so you can send from your own address.
3. Set the environment variables and inject the adapter.

```ts title="main.ts"
import { ResendEmailAdapter } from "@headless-lms/adapter-email-resend";

const container = await createContainer(config, {
  adapters: {
    email: new ResendEmailAdapter({
      apiKey: process.env.RESEND_API_KEY!,
      from: process.env.EMAIL_FROM ?? "onboarding@resend.dev",
    }),
  },
});
```

The adapter reads no environment itself — your installation parses env into a `ResendEmailConfig` and constructs it. In the reference installation, an unset `RESEND_API_KEY` means no adapter is injected and email sends fail loudly instead of silently dropping.

## Environment variables

These are the variables the reference installation (`apps/api`) maps to the adapter's config:

| Variable | Required | Maps to | Notes |
| --- | --- | --- | --- |
| `RESEND_API_KEY` | yes | `apiKey` | Unset → no adapter injected; sends fail loudly. |
| `EMAIL_FROM` | no | `from` | e.g. `Acme LMS <noreply@acme.com>`, on a verified Resend domain. Defaults to `onboarding@resend.dev`. |

## Using a different provider

Implement the `EmailSender` port from `@headless-lms/core/types` — a single `send(message)` method — and pass your implementation in the `email` slot instead.