openai-cloudflare-deploy/references/email-routing/api.md

Email Routing API Reference

Worker Runtime API

Email Handler Interface

interface ExportedHandler<Env = unknown> {
  email?(message: ForwardableEmailMessage, env: Env, ctx: ExecutionContext): void | Promise<void>;
}

ForwardableEmailMessage

Main interface for incoming emails:

interface ForwardableEmailMessage {
  readonly from: string;          // Envelope sender (e.g., "[email protected]")
  readonly to: string;             // Envelope recipient (e.g., "[email protected]")
  readonly headers: Headers;       // Web API Headers object
  readonly raw: ReadableStream;    // Raw MIME message stream

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

Key Properties:

Property	Type	Description
from	string	Envelope sender (MAIL FROM), not header From
to	string	Envelope recipient (RCPT TO), not header To
headers	Headers	Email headers (Subject, From, To, etc.)
raw	ReadableStream	Raw MIME message (consume once only)

Methods:

• setReject(reason): Reject email with bounce message
• forward(rcptTo, headers?): Forward to verified destination, optionally add headers

Headers Object

Standard Web API Headers interface:

// Access headers
const subject = message.headers.get("subject");
const from = message.headers.get("from");
const messageId = message.headers.get("message-id");

// Check spam score
const spamScore = parseFloat(message.headers.get("x-cf-spamh-score") || "0");
if (spamScore > 5) {
  message.setReject("Spam detected");
}

Common Headers

subject, from, to, x-cf-spamh-score (spam score), message-id (deduplication), dkim-signature (auth)

Envelope vs Header Addresses

Critical distinction:

// Envelope addresses (routing, auth checks)
message.from // "[email protected]" (actual sender)
message.to   // "[email protected]" (your address)

// Header addresses (display, user-facing)
message.headers.get("from") // "Alice <[email protected]>"
message.headers.get("to")   // "Bob <[email protected]>"

Use envelope addresses for: - Authentication/SPF checks - Routing decisions - Bounce handling

Use header addresses for: - Display to users - Reply-To logic - User-facing filtering

SendEmail Binding

Outbound email API for transactional messages.

Configuration

// wrangler.jsonc
{
  "send_email": [
    { "name": "EMAIL" }
  ]
}

TypeScript Types

interface Env {
  EMAIL: SendEmail;
}

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

interface EmailMessage {
  from: string | { name?: string; email: string };
  to: string | { name?: string; email: string } | Array<string | { name?: string; email: string }>;
  subject: string;
  text?: string;
  html?: string;
  headers?: Headers;
  reply_to?: string | { name?: string; email: string };
}

Send Email Example

interface Env {
  EMAIL: SendEmail;
}

export default {
  async fetch(request, env, ctx): Promise<Response> {
    await env.EMAIL.send({
      from: { name: "Acme Corp", email: "[email protected]" },
      to: [
        { name: "Alice", email: "[email protected]" },
        "[email protected]"
      ],
      subject: "Your order #12345 has shipped",
      text: "Track your package at: https://track.example.com/12345",
      html: "<p>Track your package at: <a href='https://track.example.com/12345'>View tracking</a></p>",
      reply_to: { name: "Support", email: "[email protected]" }
    });

    return new Response("Email sent");
  }
} satisfies ExportedHandler<Env>;

SendEmail Constraints

• From address: Must be on verified domain (your domain with Email Routing enabled)
• Volume limits: Transactional only, no bulk/marketing email
• Rate limits: 100 emails/minute on Free plan, higher on Paid
• No attachments: Use links to hosted files instead
• No DKIM control: Cloudflare signs automatically

REST API Operations

Base URL: https://api.cloudflare.com/client/v4

Authentication

curl -H "Authorization: Bearer $API_TOKEN" https://api.cloudflare.com/client/v4/...

Key Endpoints

Operation	Method	Endpoint
Enable routing	POST	/zones/{zone_id}/email/routing/enable
Disable routing	POST	/zones/{zone_id}/email/routing/disable
List rules	GET	/zones/{zone_id}/email/routing/rules
Create rule	POST	/zones/{zone_id}/email/routing/rules
Verify destination	POST	/zones/{zone_id}/email/routing/addresses
List destinations	GET	/zones/{zone_id}/email/routing/addresses

Create Routing Rule Example

curl -X POST "https://api.cloudflare.com/client/v4/zones/$ZONE_ID/email/routing/rules" \
  -H "Authorization: Bearer $API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "enabled": true,
    "name": "Forward sales",
    "matchers": [{"type": "literal", "field": "to", "value": "[email protected]"}],
    "actions": [{"type": "forward", "value": ["[email protected]"]}],
    "priority": 0
  }'

Matcher types: literal (exact match), all (catch-all).