Envoyer un email depuis un Worker Cloudflare

mkdir contact-form && cd contact-form
npm init -y
npm install @mailkube/mailkube-node
npm install --save-dev [email protected]
mkdir public src

{
  "name": "contact-form",
  "main": "src/index.js",
  "compatibility_date": "2026-10-01",
  "assets": { "directory": "./public" }
}

<form method="post" action="/api/contact">
  <label>Nom <input name="name" required maxlength="100"></label>
  <label>Email <input type="email" name="email" required></label>
  <label>Message <textarea name="message" required maxlength="5000"></textarea></label>
  <p>Nous conservons votre adresse IP et votre pays avec votre message.</p>
  <button type="submit">Envoyer</button>
</form>

import { ApiError, Mailkube } from '@mailkube/mailkube-node';

export default {
  async fetch(request, env) {
    const url = new URL(request.url);
    if (url.pathname !== '/api/contact' || request.method !== 'POST') {
      return new Response('Introuvable', { status: 404 });
    }

    const form = await request.formData();
    const name = String(form.get('name') ?? '');
    const email = String(form.get('email') ?? '');
    const message = String(form.get('message') ?? '');

    const ip = request.headers.get('CF-Connecting-IP') ?? 'unknown';
    const country = request.headers.get('CF-IPCountry') ?? 'unknown';
    const page = sameSite(request.headers.get('Referer'), url);

    const client = new Mailkube({ apiKey: env.MAILKUBE_API_KEY, timeoutMs: 8000 });

    try {
      await client.emails.send({
        from: 'Formulaire de contact <[email protected]>',
        to: '[email protected]',
        replyTo: email,
        subject: `Nouveau message de ${name}`,
        html: `<h2>Nouveau message de ${escapeHtml(name)}</h2>`
          + `<p><b>Email :</b> ${escapeHtml(email)}</p>`
          + `<p>${escapeHtml(message).replaceAll('\n', '<br>')}</p>`
          + `<hr><p style="color:#6b7280;font-size:12px">`
          + `Envoyé depuis <a href="${escapeHtml(page)}">${escapeHtml(page)}</a>`
          + ` · IP ${escapeHtml(ip)} · ${escapeHtml(flag(country))}</p>`,
        text: `${name} <${email}>\n\n${message}\n\nEnvoyé depuis ${page} · IP ${ip} · ${flag(country)}`,
        idempotencyKey: await fingerprint(name, email, message),
      });
    } catch (error) {
      console.error(error instanceof ApiError
        ? `${error.statusCode} ${error.errorName} (request ${error.requestId})`
        : error);
      return new Response("Votre message n'a pas pu être envoyé, réessayez.", { status: 502 });
    }

    return Response.redirect(new URL('/thanks.html', url), 303);
  },
};

function flag(country) {
  if (!/^[A-Z]{2}$/.test(country) || country === 'XX') return country;
  return String.fromCodePoint(...[...country].map((c) => 0x1f1a5 + c.charCodeAt(0)));
}

function escapeHtml(value) {
  return value.replace(/[&<>"']/g, (c) => `&#${c.charCodeAt(0)};`);
}

function sameSite(referer, url) {
  try {
    return new URL(referer).origin === url.origin ? referer : url.origin;
  } catch {
    return url.origin;
  }
}

async function fingerprint(...parts) {
  const bytes = new TextEncoder().encode(parts.join('\n'));
  const digest = await crypto.subtle.digest('SHA-256', bytes);
  return [...new Uint8Array(digest)].map((b) => b.toString(16).padStart(2, '0')).join('');
}

npx wrangler deploy

Uploaded contact-form
Deployed contact-form triggers
  https://contact-form.<your-subdomain>.workers.dev

npx wrangler secret put MAILKUBE_API_KEY

curl -i https://contact-form.<your-subdomain>.workers.dev/api/contact \
  -d name='Claire Dubois' \
  -d email=[email protected] \
  -d message='Test du formulaire de contact'

HTTP/2 303
location: https://contact-form.<your-subdomain>.workers.dev/thanks.html

<script src="https://challenges.cloudflare.com/turnstile/v0/api.js" async defer></script>

<form method="post" action="/api/contact">
  <!-- champs name, email et message comme avant -->
  <div class="cf-turnstile" data-sitekey="YOUR_SITE_KEY"></div>
  <button type="submit">Envoyer</button>
</form>

npx wrangler secret put TURNSTILE_SECRET_KEY

const check = await fetch('https://challenges.cloudflare.com/turnstile/v0/siteverify', {
  method: 'POST',
  body: new URLSearchParams({
    secret: env.TURNSTILE_SECRET_KEY,
    response: String(form.get('cf-turnstile-response') ?? ''),
  }),
});
if (!(await check.json()).success) {
  return new Response('Confirmez que vous êtes humain, puis réessayez.', { status: 403 });
}