cloudflare-email-routing

Cloudflare Email Routing

Status: Production Ready ✅ | Last Verified: 2025-11-18

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What Is Email Routing?

Two capabilities:

1. Email Workers - Receive and process incoming emails (allowlists, forwarding, parsing)
2. Send Email - Send emails from Workers to verified addresses

Both free and work together for complete email functionality.

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Quick Start (10 Minutes)

Part 1: Enable Email Routing

Dashboard setup:

1. Dashboard → Domain → Email → Email Routing
2. Enable Email Routing → Add records and enable
3. Create destination address:
   • Custom: hello@yourdomain.com
   • Destination: Your email
   • Verify via email
4. ✅ Basic forwarding active

Part 2: Receiving Emails (Email Workers)

Install dependencies:

bun add postal-mime@2.5.0 mimetext@3.0.27

Create email worker:

// src/email.ts
import { EmailMessage } from 'cloudflare:email';
import PostalMime from 'postal-mime';

export default {
  async email(message, env, ctx) {
    const parser = new PostalMime.default();
    const email = await parser.parse(await new Response(message.raw).arrayBuffer());

    console.log('From:', message.from);
    console.log('Subject:', email.subject);

    // Forward to destination
    await message.forward('you@gmail.com');
  }
};

Configure wrangler.jsonc:

{
  "name": "email-worker",
  "main": "src/email.ts",
  "compatibility_date": "2025-10-11",  // must be >= 2024-09-23 for nodejs_compat
  "compatibility_flags": ["nodejs_compat"]  // Required! postal-mime needs Node.js compat
}

Deploy and connect:

bunx wrangler deploy

Dashboard → Email Workers → Create address → Select worker

Part 3: Sending Emails

Add send email binding:

{
  "name": "my-worker",
  "main": "src/index.ts",
  "compatibility_date": "2025-10-11",
  "send_email": [
    {
      "name": "SES",
      "destination_address": "user@example.com"
    }
  ]
}

Send from worker:

import { EmailMessage } from 'cloudflare:email';
import { createMimeMessage } from 'mimetext';

const msg = createMimeMessage();
msg.setSender({ name: 'App', addr: 'noreply@yourdomain.com' });
msg.setRecipient('user@example.com');
msg.setSubject('Hello!');
msg.addMessage({
  contentType: 'text/plain',
  data: 'Email body here'
});

const message = new EmailMessage(
  'noreply@yourdomain.com',
  'user@example.com',
  msg.asRaw()
);

await env.SES.send(message);

Load references/setup-guide.md for complete walkthrough.

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Critical Rules

Always Do ✅

1. Enable compatibility_flags: ["nodejs_compat"] for postal-mime (requires compatibility_date >= 2024-09-23)
2. Verify destination addresses before sending
3. Parse with postal-mime for email content
4. Use mimetext for creating emails
5. Check message.from for allowlists
6. Forward with message.forward() (not manual)
7. Handle errors (email delivery can fail)
8. Test with real emails (not just dashboard)
9. Add MX records (automatic via dashboard)
10. Log email activity for debugging

Never Do ❌

1. Never skip nodejs_compat (postal-mime requires the Node.js compat flag)
2. Never send without verification (delivery fails)
3. Never hardcode email addresses in public code
4. Never skip parsing (raw email is hard to work with)
5. Never ignore spam (implement allowlists/blocklists)
6. Never exceed Gmail limits (500 emails/day to Gmail)
7. Never skip error handling (emails can fail)
8. Never modify DNS manually (use dashboard)
9. Never expose email content in logs (PII)
10. Never assume instant delivery (email is async)

---

Common Patterns

Allowlist

const allowlist = ['approved@domain.com'];

if (!allowlist.includes(message.from)) {
  message.setReject('Not on allowlist');
  return;
}

await message.forward('you@gmail.com');

Blocklist

const blocklist = ['spam@bad.com'];

if (blocklist.includes(message.from)) {
  message.setReject('Blocked');
  return;
}

await message.forward('you@gmail.com');

Reply to Email

const msg = createMimeMessage();
msg.setSender({ addr: 'noreply@yourdomain.com' });
msg.setRecipient(message.from);
msg.setSubject(`Re: ${email.subject}`);
msg.addMessage({
  contentType: 'text/plain',
  data: 'Thanks for your email!'
});

const reply = new EmailMessage(
  'noreply@yourdomain.com',
  message.from,
  msg.asRaw()
);

await env.SES.send(reply);

Parse Attachments

const parser = new PostalMime.default();
const email = await parser.parse(await new Response(message.raw).arrayBuffer());

for (const attachment of email.attachments) {
  console.log('Filename:', attachment.filename);
  console.log('Type:', attachment.mimeType);
  console.log('Size:', attachment.content.byteLength);
}

Custom Routing Logic

async email(message, env, ctx) {
  const parser = new PostalMime.default();
  const email = await parser.parse(await new Response(message.raw).arrayBuffer());

  // Route based on subject
  if (email.subject.includes('[Support]')) {
    await message.forward('support@yourdomain.com');
  } else if (email.subject.includes('[Sales]')) {
    await message.forward('sales@yourdomain.com');
  } else {
    await message.forward('general@yourdomain.com');
  }
}

---

Email Message Properties

Incoming Messages (ForwardableEmailMessage)

message.from        // Sender email
message.to          // Recipient email
message.headers     // Email headers
message.raw         // Raw email stream
message.rawSize     // Size in bytes

// Methods
message.forward(address)        // Forward to address
message.setReject(reason)       // Reject email

Parsed Email (PostalMime)

email.from          // { name, address }
email.to            // [{ name, address }]
email.subject       // Subject line
email.text          // Plain text body
email.html          // HTML body
email.attachments   // Array of attachments
email.headers       // All headers

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Top 5 Errors Prevented

1. "Email Trigger not available": Enable compatibility_flags: ["nodejs_compat"] (with compatibility_date >= 2024-09-23)
2. Destination not verified: Verify all send destinations
3. Gmail rate limit: Max 500 emails/day to Gmail
4. SPF permerror: Use dashboard to configure DNS
5. Worker call failed: Check logs for parsing errors

---

Use Cases

Use Case 1: Support Ticket System

async email(message, env, ctx) {
  const parser = new PostalMime.default();
  const email = await parser.parse(await new Response(message.raw).arrayBuffer());

  // Create ticket in database
  await env.DB.prepare(
    'INSERT INTO tickets (email, subject, body, created_at) VALUES (?, ?, ?, ?)'
  ).bind(message.from, email.subject, email.text, Date.now()).run();

  // Send confirmation
  const msg = createMimeMessage();
  msg.setSender({ addr: 'support@yourdomain.com' });
  msg.setRecipient(message.from);
  msg.setSubject('Ticket Created');
  msg.addMessage({
    contentType: 'text/plain',
    data: 'Your support ticket has been created.'
  });

  const confirmation = new EmailMessage(
    'support@yourdomain.com',
    message.from,
    msg.asRaw()
  );

  await env.SES.send(confirmation);
}

Use Case 2: Email Notifications

export default {
  async fetch(request, env, ctx) {
    // User signup
    const { email, name } = await request.json();

    const msg = createMimeMessage();
    msg.setSender({ name: 'App', addr: 'noreply@yourdomain.com' });
    msg.setRecipient(email);
    msg.setSubject('Welcome!');
    msg.addMessage({
      contentType: 'text/html',
      data: `<h1>Welcome, ${name}!</h1>`
    });

    const message = new EmailMessage(
      'noreply@yourdomain.com',
      email,
      msg.asRaw()
    );

    await env.SES.send(message);

    return new Response('Welcome email sent!');
  }
};

Use Case 3: Email Forwarding with Filtering

async email(message, env, ctx) {
  const parser = new PostalMime.default();
  const email = await parser.parse(await new Response(message.raw).arrayBuffer());

  // Filter spam keywords
  const spamKeywords = ['viagra', 'lottery', 'prince'];
  const isSpam = spamKeywords.some(keyword =>
    email.subject.toLowerCase().includes(keyword) ||
    email.text.toLowerCase().includes(keyword)
  );

  if (isSpam) {
    message.setReject('Spam detected');
    return;
  }

  await message.forward('you@gmail.com');
}

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When to Load References

Load references/setup-guide.md when:

• First-time Email Routing setup
• Configuring MX records
• Setting up email workers
• Configuring send email binding
• Complete walkthrough needed

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Using Bundled Resources

References (references/):

• setup-guide.md - Complete setup walkthrough (enabling routing, email workers, send email)
• common-errors.md - All 8 documented errors with solutions and prevention
• dns-setup.md - MX records, SPF, DKIM configuration guide
• local-development.md - Local testing and development patterns

Templates (templates/):

• receive-basic.ts - Basic email receiving worker
• receive-allowlist.ts - Email allowlist implementation
• receive-blocklist.ts - Email blocklist implementation
• receive-reply.ts - Auto-reply email worker
• send-basic.ts - Basic send email example
• send-notification.ts - Notification email pattern
• wrangler-email.jsonc - Wrangler configuration for email routing

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Official Documentation

• Email Routing: https://developers.cloudflare.com/email-routing/
• Email Workers: https://developers.cloudflare.com/email-routing/email-workers/
• Send Email: https://developers.cloudflare.com/email-routing/email-workers/send-email-workers/

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Questions? Issues?

1. Check references/setup-guide.md for complete setup
2. Verify compatibility_flags: ["nodejs_compat"] in wrangler.jsonc
3. Confirm destination addresses verified
4. Check logs for errors