Cloudflare Email Routing

Cloudflare Email Routing

Status: Production Ready ✅ Last Updated: 2025-10-23 Latest Versions: [email protected], [email protected]

---

What is Cloudflare Email Routing?

Cloudflare Email Routing provides two complementary capabilities:

1. Email Workers - Receive and process incoming emails with custom logic (allowlists, blocklists, forwarding, parsing, replying)
2. Send Email - Send emails from Workers to verified destination addresses (notifications, alerts, confirmations)

Both capabilities are free and work together to enable complete email functionality in Cloudflare Workers.

---

Quick Start (10 Minutes)

Part 1: Enable Email Routing (Dashboard)

Prerequisites: Domain must be on Cloudflare DNS

1. Log in to Cloudflare Dashboard → select your domain
2. Go to Email > Email Routing
3. Select Enable Email Routing → Add records and enable
   • This automatically adds MX records, SPF, and DKIM to your DNS
4. Create a destination address:
   • Custom address: [email protected]
   • Destination: Your personal email (e.g., [email protected])
   • Verify the destination address via email
5. ✅ Basic email forwarding is now active

What you just did: Configured DNS and basic forwarding. Now let's add Workers for custom logic.

---

Part 2: Receiving Emails with Email Workers

1. Install Dependencies

npm install [email protected] [email protected]

Why these packages:

• postal-mime - Parse incoming email messages (headers, body, attachments)
• mimetext - Create email messages for sending/​replying

2. Create Email Worker

Create src/​email.ts:

import { EmailMessage } from 'cloudflare:email';
import PostalMime from 'postal-mime';

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

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

    // Forward to verified destination
    await message.forward('[email protected]');
  },
};

3. Configure Wrangler

Update wrangler.jsonc:

{
  "name": "email-worker",
  "main": "src/​email.ts",
  "compatibility_date": "2025-10-11"
}

4. Deploy and Bind

npx wrangler deploy

# In Cloudflare Dashboard:
# Email > Email Routing > Email Workers
# Select your worker → Create route → Enter address (e.g., [email protected])

What you just did: Created a Worker that logs and forwards emails.

---

Part 3: Sending Emails from Workers

1. Configure Send Email Binding

Update wrangler.jsonc:

{
  "name": "my-worker",
  "main": "src/​index.ts",
  "compatibility_date": "2025-10-11",
  "send_email": [
    {
      "name": "EMAIL",
      "destination_address": "[email protected]"
    }
  ]
}

CRITICAL: destination_address must be:

• A domain where you have Email Routing enabled
• A verified destination address in Email Routing settings

2. Send Email from Worker

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

export default {
  async fetch(request, env, ctx) {
    // Create email message
    const msg = createMimeMessage();
    msg.setSender({ name: 'My App', addr: '[email protected]' });
    msg.setRecipient('[email protected]');
    msg.setSubject('Welcome to My App');
    msg.addMessage({
      contentType: 'text/​plain',
      data: 'Thank you for signing up!',
    });

    // Send via binding
    const message = new EmailMessage(
      '[email protected]',
      '[email protected]',
      msg.asRaw()
    );

    await env.EMAIL.send(message);

    return new Response('Email sent!');
  },
};

3. Deploy

npx wrangler deploy

What you just did: Configured your Worker to send emails to verified addresses.

---

Email Workers: Complete Guide

Runtime API

EmailEvent Handler

export default {
  async email(message: ForwardableEmailMessage, env: Env, ctx: ExecutionContext) {
    // Process email here
  },
};

Parameters:

• message - ForwardableEmailMessage object
• env - Environment bindings (KV, D1, secrets, etc.)
• ctx - Execution context (waitUntil for async operations)

ForwardableEmailMessage Properties

interface ForwardableEmailMessage {
  readonly from: string;          // Sender email
  readonly to: string;            // Recipient email
  readonly headers: Headers;      // Email headers
  readonly raw: ReadableStream;   // Raw email message
  readonly rawSize: number;       // Size in bytes

  // Methods
  setReject(reason: string): void;
  forward(rcptTo: string, headers?: Headers): Promise<void>;
  reply(message: EmailMessage): Promise<void>;
}

---

Common Patterns

Pattern 1: Allowlist

Only accept emails from approved senders:

export default {
  async email(message, env, ctx) {
    const allowList = [
      '[email protected]',
      '[email protected]',
      '[email protected]',
    ];

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

    await message.forward('[email protected]');
  },
};

When to use: Contact forms, private email addresses, team inboxes

---

Pattern 2: Blocklist

Reject emails from specific senders or domains:

export default {
  async email(message, env, ctx) {
    const blockList = [
      '[email protected]',
      '@suspicious-domain.com', // Block entire domain
    ];

    const isBlocked = blockList.some(pattern =>
      message.from.includes(pattern)
    );

    if (isBlocked) {
      message.setReject('Sender blocked');
      return;
    }

    await message.forward('[email protected]');
  },
};

When to use: Spam filtering, blocking harassers, domain-level blocks

---

Pattern 3: Parse and Store

Extract email content and store in D1 or KV:

import PostalMime from 'postal-mime';

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

    // Store in D1
    await env.DB.prepare(
      'INSERT INTO emails (from_addr, subject, text, received_at) VALUES (?, ?, ?, ?)'
    ).bind(
      message.from,
      email.subject,
      email.text,
      new Date().toISOString()
    ).run();

    // Forward to inbox
    await message.forward('[email protected]');
  },
};

When to use: Email archiving, ticket systems, support inboxes, audit logs

---

Pattern 4: Auto-Reply

Send automatic replies with custom logic:

import PostalMime from 'postal-mime';
import { createMimeMessage } from 'mimetext';
import { EmailMessage } from 'cloudflare:email';

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

    // Create reply
    const msg = createMimeMessage();
    msg.setSender({ name: 'Support Team', addr: '[email protected]' });
    msg.setRecipient(message.from);
    msg.setHeader('In-Reply-To', message.headers.get('Message-ID'));
    msg.setSubject(`Re: ${email.subject}`);
    msg.addMessage({
      contentType: 'text/​plain',
      data: `Thank you for your message about "${email.subject}". We'll respond within 24 hours.`,
    });

    // Send reply
    const replyMessage = new EmailMessage(
      '[email protected]',
      message.from,
      msg.asRaw()
    );

    await message.reply(replyMessage);

    // Also forward to team inbox
    await message.forward('[email protected]');
  },
};

When to use: Out-of-office replies, support ticket acknowledgments, automated responses

---

Pattern 5: Conditional Routing

Route emails to different destinations based on content:

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());

    const subject = email.subject.toLowerCase();

    // Route based on subject keywords
    if (subject.includes('urgent') || subject.includes('critical')) {
      await message.forward('[email protected]');
    } else if (subject.includes('invoice') || subject.includes('payment')) {
      await message.forward('[email protected]');
    } else if (subject.includes('support') || subject.includes('help')) {
      await message.forward('[email protected]');
    } else {
      await message.forward('[email protected]');
    }
  },
};

When to use: Department routing, priority filtering, category-based inboxes

---

Send Email: Complete Guide

Configuration

Single Destination (Simple)

{
  "send_email": [
    {
      "name": "EMAIL",
      "destination_address": "[email protected]"
    }
  ]
}

Behavior: All emails sent via env.EMAIL go to this address.

Multiple Destinations (Flexible)

{
  "send_email": [
    {
      "name": "EMAIL",
      "allowed_destination_addresses": [
        "[email protected]",
        "[email protected]",
        "[email protected]"
      ]
    }
  ]
}

Behavior: Can send to any address in the list.

Multiple Bindings (Organized)

{
  "send_email": [
    {
      "name": "NOTIFICATIONS",
      "destination_address": "[email protected]"
    },
    {
      "name": "ALERTS",
      "destination_address": "[email protected]"
    }
  ]
}

Behavior: Use different bindings for different purposes.

---

Sending Emails

Basic Text Email

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

const msg = createMimeMessage();
msg.setSender({ name: 'My App', addr: '[email protected]' });
msg.setRecipient('[email protected]');
msg.setSubject('Welcome!');
msg.addMessage({
  contentType: 'text/​plain',
  data: 'Welcome to our service!',
});

const email = new EmailMessage(
  '[email protected]',
  '[email protected]',
  msg.asRaw()
);

await env.EMAIL.send(email);

HTML Email

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

const msg = createMimeMessage();
msg.setSender({ name: 'My App', addr: '[email protected]' });
msg.setRecipient('[email protected]');
msg.setSubject('Welcome!');

// Add both plain text and HTML versions
msg.addMessage({
  contentType: 'text/​plain',
  data: 'Welcome to our service!',
});

msg.addMessage({
  contentType: 'text/​html',
  data: '<h1>Welcome!</​h1><p>Thanks for joining us.</​p>',
});

const email = new EmailMessage(
  '[email protected]',
  '[email protected]',
  msg.asRaw()
);

await env.EMAIL.send(email);

Email with Custom Headers

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

const msg = createMimeMessage();
msg.setSender({ name: 'My App', addr: '[email protected]' });
msg.setRecipient('[email protected]');
msg.setSubject('Password Reset');

// Add custom headers
msg.setHeader('X-Priority', '1');
msg.setHeader('X-Application-ID', 'my-app-123');

msg.addMessage({
  contentType: 'text/​plain',
  data: 'Click here to reset your password...',
});

const email = new EmailMessage(
  '[email protected]',
  '[email protected]',
  msg.asRaw()
);

await env.EMAIL.send(email);

---

DNS Configuration

Automatic Setup (Recommended)

When you enable Email Routing in the dashboard, Cloudflare automatically adds:

1. MX Records - Direct email to Cloudflare's servers

   yourdomain.com. 300 IN MX 13 amir.mx.cloudflare.net.
   yourdomain.com. 300 IN MX 86 linda.mx.cloudflare.net.
   yourdomain.com. 300 IN MX 24 isaac.mx.cloudflare.net.
   

2. SPF Record - Authorize Cloudflare to send on your behalf

   yourdomain.com. 300 IN TXT "v=spf1 include:_spf.mx.cloudflare.net ~all"
   

3. DKIM Records - Sign outgoing emails

   Automatically configured per domain
   

Manual Setup (Advanced)

If you need to migrate from another provider:

1. Go to Email > Email Routing > Settings
2. Select Start disabling > Unlock records and continue
3. Edit DNS records as needed
4. When ready, Lock DNS records to protect Email Routing

WARNING: Changing MX records will break Email Routing. Only do this if migrating providers.

---

Known Issues Prevention

This skill prevents 8 documented issues:

Issue #1: "Email Trigger not available to this workers"

Error: Testing email workers fails with "Email Trigger not available to this workers"

Source: workers-sdk #3751

Why It Happens: Wrangler dev doesn't fully support email triggers; testing must be done via deployed Workers

Prevention:

• Always deploy email workers before testing
• Use wrangler tail for live debugging
• Use dashboard "Test Email Event" feature (when working)

---

Issue #2: Destination Address Verification Bug

Error: Verified destination addresses show as "unverified" in Email Worker forwarding

Source: Community reports (Cloudflare Community)

Why It Happens: Bug in dashboard where addresses only show verified if also used in regular routing rules

Prevention:

• Create a regular forward rule for each destination address first
• Then use the same addresses in Email Workers
• Verify addresses before deploying workers

---

Issue #3: Gmail Rate Limiting

Error: "421: Our system has detected an unusual rate of unsolicited mail originating from your IP address"

Source: Community reports

Why It Happens: Gmail may flag Cloudflare's IP ranges as suspicious due to shared infrastructure

Prevention:

• Implement proper SPF/​DKIM/​DMARC records
• Don't send bulk emails through Email Routing
• Use transactional email services (e.g., SendGrid, Mailgun) for high volume
• Rate-limit your sending (max 50-100 emails/​hour for personal use)

---

Issue #4: SPF Permerror with MailChannels

Error: SPF permerror when routing through MailChannels

Source: Community discussion

Why It Happens: SPF record chain breaks when forwarding through multiple services

Prevention:

• Use Email Routing's native send capabilities instead of MailChannels
• If using MailChannels, configure SPF includes correctly
• Test with MXToolbox SPF checker

---

Issue #5: Limited Logging on Free Plan

Error: Cannot see worker logs or email processing details

Source: Community reports

Why It Happens: Free plan has limited log retention and streaming

Prevention:

• Use wrangler tail during development for live logs
• Use console.log() extensively in email workers
• Store critical data in D1/​KV for debugging
• Upgrade to Workers Paid plan for better observability

---

Issue #6: Activity Log Discrepancies

Error: Emails show as "Dropped" in Activity Log even when successfully forwarded

Source: Community reports

Why It Happens: Dashboard bug showing incorrect status

Prevention:

• Check actual email delivery instead of relying on dashboard
• Use wrangler tail to verify processing
• Implement your own logging in D1/​KV
• Test with real emails to confirm delivery

---

Issue #7: Test Email Event Loading Indefinitely

Error: Dashboard "Test Email Event" button remains in loading state forever

Source: workers-sdk #9195

Why It Happens: Bug in dashboard testing interface (unresolved as of 2025-10)

Prevention:

• Don't rely on dashboard testing feature
• Use curl with local development instead (see Local Development section)
• Deploy and test with real emails
• Use wrangler tail to monitor processing

---

Issue #8: Worker Call Failures

Error: "Rejected reason: Unknown error: failed to call worker: Worker call failed for 3 times, aborting…"

Source: workers-sdk #9069, Community reports

Why It Happens: Worker crashes due to runtime errors, timeouts, or memory issues

Prevention:

• Add comprehensive error handling with try/​catch
• Set timeouts for external API calls
• Log errors to D1/​KV before rejecting
• Use ctx.waitUntil() for non-critical operations
• Test with various email formats (plain text, HTML, attachments)

---

Local Development

Receiving Emails

Wrangler simulates email reception via HTTP POST:

# Start dev server
npx wrangler dev

# In another terminal, send test email
curl http://localhost:8787 -X POST \
  --data-binary @- << EOF
From: [email protected]
To: [email protected]
Subject: Test Email

This is a test email body.
EOF

What happens: Wrangler logs the email processing and shows where forwarded emails would go.

Sending Emails

Wrangler writes sent emails to local .eml files:

// Your worker code
await env.EMAIL.send(message);

Output in terminal:

[wrangler:inf] send_email binding called with the following message:
  /​tmp/​miniflare-abc123/​files/​email/​message-123.eml

View the email:

cat /​tmp/​miniflare-abc123/​files/​email/​message-123.eml

---

Configuration Files Reference

Complete wrangler.jsonc (Both Receive + Send)

{
  "$schema": "node_modules/​wrangler/​config-schema.json",
  "name": "email-worker",
  "main": "src/​email.ts",
  "account_id": "YOUR_ACCOUNT_ID",
  "compatibility_date": "2025-10-11",
  "observability": {
    "enabled": true
  },

  // Send email binding
  "send_email": [
    {
      "name": "NOTIFICATIONS",
      "destination_address": "[email protected]"
    },
    {
      "name": "ALERTS",
      "allowed_destination_addresses": [
        "[email protected]",
        "[email protected]"
      ]
    }
  ],

  // Optional: Add other bindings
  "d1_databases": [
    {
      "binding": "DB",
      "database_name": "email-archive",
      "database_id": "YOUR_DATABASE_ID"
    }
  ],

  "kv_namespaces": [
    {
      "binding": "EMAIL_CACHE",
      "id": "YOUR_KV_ID"
    }
  ]
}

---

TypeScript Types

Environment Bindings

interface Env {
  // Send email bindings
  EMAIL: SendEmail;
  NOTIFICATIONS: SendEmail;
  ALERTS: SendEmail;

  // Other bindings
  DB: D1Database;
  EMAIL_CACHE: KVNamespace;
}

interface SendEmail {
  send(message: EmailMessage): Promise<void>;
}

Full Type Definitions

import { EmailMessage } from 'cloudflare:email';

interface ForwardableEmailMessage {
  readonly from: string;
  readonly to: string;
  readonly headers: Headers;
  readonly raw: ReadableStream;
  readonly rawSize: number;

  setReject(reason: string): void;
  forward(rcptTo: string, headers?: Headers): Promise<void>;
  reply(message: EmailMessage): Promise<void>;
}

declare module 'cloudflare:email' {
  export class EmailMessage {
    constructor(from: string, to: string, raw: string | ReadableStream);
  }
}

---

Complete Setup Checklist

Email Routing Setup

• Domain is on Cloudflare DNS
• Email Routing enabled in dashboard
• MX, SPF, DKIM records automatically added
• At least one destination address verified
• Test basic forwarding with a custom address

Email Workers (Receiving)

• [email protected] installed
• [email protected] installed
• Email worker created with async email() handler
• Worker deployed: npx wrangler deploy
• Worker bound to email route in dashboard
• Test with real email to route address
• Verify logs with wrangler tail

Send Email (Sending)

• send_email binding configured in wrangler.jsonc
• destination_address or allowed_destination_addresses specified
• All destination addresses verified in Email Routing
• Worker code uses env.EMAIL.send()
• Worker deployed: npx wrangler deploy
• Test sending email via Worker endpoint
• Confirm email delivery to recipient

---

Troubleshooting

Problem: "Email Trigger not available to this workers"

Solution:

• Deploy your worker: npx wrangler deploy
• Test with real emails, not local simulation
• Use wrangler tail to monitor processing

---

Problem: "Destination address not verified"

Solution:

• Check Email Routing > Destination addresses in dashboard
• Click "Resend verification" if needed
• Create a regular forwarding rule first (workaround for bug)
• Verify all addresses before deploying workers

---

Problem: Gmail rejects emails with 421 error

Solution:

• Verify SPF/​DKIM records are configured (automatic with Email Routing)
• Reduce sending rate (max 50-100/​hour for personal use)
• Don't send unsolicited emails or bulk mail
• Consider transactional email service for high volume

---

Problem: Emails not forwarding from Email Worker

Solution:

• Check worker is bound to correct email route in dashboard
• Verify destination address is verified
• Use wrangler tail to see processing logs
• Check for errors in worker code (try/​catch around forward())
• Confirm MX records are still pointing to Cloudflare

---

Problem: Cannot see worker logs

Solution:

• Use wrangler tail --format pretty for live logs
• Add extensive console.log() statements in worker
• Store debug info in D1 or KV for later inspection
• Upgrade to Workers Paid plan for better log retention

---

Problem: Worker crashes with "failed to call worker"

Solution:

• Add try/​catch error handling around all operations
• Set timeouts for external API calls
• Test with different email formats (plain text, HTML, attachments)
• Check worker doesn't exceed CPU/​memory limits
• Use ctx.waitUntil() for non-blocking operations

---

Advanced Topics

Parsing Email Attachments

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());

    // Access attachments
    if (email.attachments && email.attachments.length > 0) {
      for (const attachment of email.attachments) {
        console.log('Attachment:', attachment.filename);
        console.log('Type:', attachment.mimeType);
        console.log('Size:', attachment.content.length);

        // Store in R2
        await env.BUCKET.put(
          `emails/​${Date.now()}-${attachment.filename}`,
          attachment.content
        );
      }
    }

    await message.forward('[email protected]');
  },
};

---

Email-Based Task Creation

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());

    // Extract task from email subject
    const taskMatch = email.subject.match(/\[TASK\](.*)/​i);

    if (taskMatch) {
      const taskDescription = taskMatch[1].trim();

      // Create task in D1
      await env.DB.prepare(
        'INSERT INTO tasks (description, created_by, created_at) VALUES (?, ?, ?)'
      ).bind(
        taskDescription,
        message.from,
        new Date().toISOString()
      ).run();

      // Send confirmation
      await message.reply(new EmailMessage(
        '[email protected]',
        message.from,
        `Task created: ${taskDescription}`
      ));
    }
  },
};

---

Email-Triggered Workflows

export default {
  async email(message, env, ctx) {
    // Trigger Cloudflare Workflow based on email
    if (message.from.endsWith('@trusted-domain.com')) {
      await env.WORKFLOW.create({
        params: {
          emailFrom: message.from,
          emailTo: message.to,
          receivedAt: new Date().toISOString(),
        },
      });
    }

    await message.forward('[email protected]');
  },
};

---

Dependencies

Required:

• [email protected] - Parse incoming email messages
• [email protected] - Create email messages for sending

Built-in:

• cloudflare:email - EmailMessage class (no installation needed)

Optional:

• @cloudflare/​workers-types - TypeScript type definitions

---

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/
• Runtime API: https://developers.cloudflare.com/email-routing/email-workers/runtime-api/
• Local Development: https://developers.cloudflare.com/email-routing/email-workers/local-development/
• postal-mime: https://www.npmjs.com/package/postal-mime
• mimetext: https://www.npmjs.com/package/mimetext

---

Package Versions (Verified 2025-10-23)

{
  "dependencies": {
    "postal-mime": "^2.5.0",
    "mimetext": "^3.0.27"
  },
  "devDependencies": {
    "@cloudflare/​workers-types": "^4.20251014.0",
    "wrangler": "^4.44.0"
  }
}

---

Questions? Issues?

1. Check references/​common-errors.md for detailed troubleshooting
2. Review references/​dns-setup.md for DNS configuration help
3. See references/​local-development.md for testing patterns
4. Check official docs: https://developers.cloudflare.com/email-routing/
5. Use wrangler tail for live debugging
6. Verify all destination addresses are verified in dashboard