cloudflare--workers-sdk/fixtures/email-worker

Email Worker Fixture

This fixture demonstrates both the EmailMessage API (raw MIME) and the MessageBuilder API for sending emails in Cloudflare Workers.

Running Locally

Start the development server:

pnpm start
# or
wrangler dev

Available Routes

EmailMessage API (Raw MIME)

GET /send - Original API using manual MIME construction

• Uses the mimetext library to build MIME messages
• Sends via LIST_SEND binding

MessageBuilder API

GET /send-simple - Simple text-only email

• Basic MessageBuilder example with plain text
• Demonstrates named sender: { name: "Alice", email: "..." }

GET /send-html - Email with text and HTML versions

• Shows how to include both text and html content
• HTML includes inline CSS styling

GET /send-attachment - Email with single text attachment

• Demonstrates attaching a text file
• Uses TextEncoder to create content

GET /send-multi-attachment - Email with multiple attachments

• Includes three different attachment types:
  • Text file (.txt)
  • JSON file (.json)
  • Binary file (simulated .pdf)
• Shows both text and HTML content

GET /send-complex - Complex email with multiple recipients

• Multiple TO recipients (with and without names)
• CC recipient with name
• BCC recipient (array)
• Both text and HTML content

Testing Bindings

GET /test-bindings - Test all three email binding types

• UNBOUND_SEND - No restrictions on recipients
• SPECIFIC_SEND - Only allows something@example.com
• LIST_SEND - Allows something@example.com and else@example.com

What to Expect

When you send emails using these routes:

1. Console Output: Miniflare logs details about the email being sent
2. File Paths: For MessageBuilder emails, you'll see temp file paths:
   • Text content → .txt files
   • HTML content → .html files
   • Attachments → Files with their original extensions

Example Console Output

send_email binding called with MessageBuilder:
From: "Alice" <sender@penalosa.cloud>
To: else@example.com
Subject: Simple MessageBuilder Test

Text: /var/folders/.../email-text/abc-123.txt

You can open these files in your editor or browser to inspect the email content.

Email Bindings Configuration

This fixture has three email bindings configured in wrangler.jsonc:

{
	"send_email": [
		{
			"name": "UNBOUND_SEND",
			// No restrictions
		},
		{
			"name": "SPECIFIC_SEND",
			"destination_address": "something@example.com",
			// Only allows sending to this specific address
		},
		{
			"name": "LIST_SEND",
			"allowed_destination_addresses": [
				"something@example.com",
				"else@example.com",
			],
			// Only allows sending to addresses in this list
		},
	],
}

Notes

• Type assertions (as any) are used because @cloudflare/workers-types doesn't yet include MessageBuilder types
• At runtime in Miniflare, the MessageBuilder API works correctly
• The allowed_sender_addresses configuration is not included in this fixture, so any sender address is accepted