Resend

Overview

@i18n-email/resend wraps a Resend instance so that emails.send() accepts an optional locale field. When locale is set, the email is translated before it is sent. When it is omitted, the call passes through to Resend unchanged.

All other Resend methods — emails.get, emails.cancel, contacts, domains, etc. — are untouched.

Installation

bun add @i18n-email/resend
# or
npm install @i18n-email/resend

Peer dependencies: i18n-email >= 0.2.0, resend >= 4, react >= 18.

Setup

Call withResend once, passing a Resend instance and the same config object that createI18nEmail accepts.

import { Resend } from "resend";
import { withResend } from "@i18n-email/resend";

const resend = withResend(new Resend(process.env.RESEND_API_KEY!), {
  openaiApiKey: process.env.OPENAI_API_KEY!,
});

The returned value is an I18nResend — a prototypal delegate of the original Resend instance with emails.send replaced.

Sending a translated email

Add locale to any emails.send call to trigger translation.

import { WelcomeEmail } from "./emails/welcome";

await resend.emails.send({
  from: "hello@acme.com",
  to: "user@example.com",
  locale: "fr",
  subject: "Welcome!",
  react: <WelcomeEmail name="Dan" />,
});

Under the hood this:

1. Translates subject and the rendered HTML to French
2. Strips locale and react from the payload
3. Calls resend.emails.send with the translated subject and html

Without locale

Omit locale and the call is forwarded to Resend exactly as-is — no translation, no overhead.

await resend.emails.send({
  from: "hello@acme.com",
  to: "user@example.com",
  subject: "Welcome!",
  html: "<p>Hello!</p>",
});

With raw HTML

Pass html instead of react if you already have a rendered HTML string.

await resend.emails.send({
  from: "hello@acme.com",
  to: "user@example.com",
  locale: "de",
  subject: "Welcome!",
  html: "<h1>Welcome!</h1><p>Your account has been created.</p>",
});

All i18n-email options

withResend accepts the full I18nEmailConfig as its second argument — including model, baseURL, maxRetries, batchSize, cache, and onTranslate.

import { Redis } from "@upstash/redis";

const redis = Redis.fromEnv();

const resend = withResend(new Resend(process.env.RESEND_API_KEY!), {
  openaiApiKey: process.env.OPENAI_API_KEY!,
  model: "gpt-4o-mini",
  batchSize: 30,
  onTranslate: ({ locale, detectedLocale, strings, cacheHit }) => {
    console.log(`[i18n] ${detectedLocale} → ${locale} | cache: ${cacheHit}`);
  },
});

API reference

withResend(resend, config)

Returns I18nResend.

I18nSendPayload

The payload type accepted by the wrapped emails.send. Extends Resend's CreateEmailOptions with one additional field:

I18nResend

The return type of withResend. Extends Resend with emails.send replaced by the locale-aware version. All other members are inherited from the original instance.

Error handling

The wrapper throws descriptive errors in these cases:

Translation errors from i18n-email are propagated as-is.