# Fallbacks and retries (/docs/concepts/fallbacks-and-retries)



Retries happen inside one adapter. Fallbacks happen after an adapter fails.

```ts
const email = createEmailClient({
  adapters: [
    resend({ apiKey: process.env.RESEND_API_KEY! }),
    smtp({
      host: "smtp.purelymail.com",
      port: 587,
      auth: {
        user: process.env.SMTP_USER!,
        pass: process.env.SMTP_PASS!,
      },
    }),
  ],
  retry: {
    retries: 1,
  },
  fallback: ["smtp"],
});
```

In this setup, Email SDK tries Resend first. If Resend fails with a retryable error, it retries once. If it still fails, it tries SMTP.

## Override fallback for one send [#override-fallback-for-one-send]

```ts
await email.send(message, {
  provider: "resend",
  fallbackAdapters: ["smtp"],
});
```

## Override retries for one send [#override-retries-for-one-send]

```ts
await email.send(message, {
  retries: 2,
});
```

## Retryable HTTP responses [#retryable-http-responses]

The fetch-based adapters mark these responses as retryable:

| Status | Meaning                         |
| ------ | ------------------------------- |
| `408`  | Request timeout                 |
| `409`  | Conflict                        |
| `425`  | Too early                       |
| `429`  | Rate limited                    |
| `5xx`  | Adapter or network-side failure |

Use an idempotency key for email that may be retried.

```ts
await email.send(message, {
  idempotencyKey: "receipt:order_123",
});
```