# Migrate from the Resend SDK (/docs/guides/migrate/resend)



Keep your Resend API key and verified sender. The migration changes the application boundary, not the provider account.

## Replace construction [#replace-construction]

```ts title="before.ts"
import { Resend } from "resend";
const resend = new Resend(process.env.RESEND_API_KEY);
```

```ts title="after.ts"
import { createEmailClient } from "@opencoredev/email-sdk";
import { resend } from "@opencoredev/email-sdk/resend";

const email = createEmailClient({
  adapters: [resend({ apiKey: process.env.RESEND_API_KEY! })],
});
```

## Replace sends [#replace-sends]

```ts title="after.ts"
const result = await email.send(
  {
    from: "Acme <hello@acme.com>",
    to: "user@example.com",
    subject: "Welcome",
    html: "<p>Your account is ready.</p>",
  },
  { idempotencyKey: "welcome:user_123" },
);

console.log(result.id);
```

Email SDK maps CC, BCC, reply-to, headers, attachments, tags, and `sendAt`. It rejects message metadata because the Resend adapter has no metadata mapping.

## Add a backup only when compatible [#add-a-backup-only-when-compatible]

A simple SMTP backup cannot carry Resend attachments, tags, or scheduling. Validate the complete route before queueing and keep `onUnknownDelivery: "stop"` unless you explicitly accept duplicate risk.

## Verify [#verify]

```bash
RESEND_API_KEY=re_xxx npx email-sdk doctor --adapter resend
RESEND_API_KEY=re_xxx npx email-sdk send \
  --adapter resend \
  --from hello@example.com \
  --to user@example.com \
  --subject "Migration smoke test" \
  --text "Dry run only." \
  --dry-run
```

<Card title="Resend adapter" href="/docs/adapters/resend" description="See all options and mapped fields." />