Email Forwarding

How It Works

Chatterbox3000 uses Cloudflare’s native send_email Worker binding to forward approved emails. No external SMTP relay or third-party service is needed.

When you approve an email in the extension:

1. The API updates the email status to approved
2. The worker constructs a MIME message and sends it via the send_email binding
3. On success, the status is updated to forwarded

The forwarded email includes:

• A classification tag in the subject (e.g., [cold_outreach] Original Subject)
• The original sender in the body
• The body preview text

Classification Tags in Subject

Forwarded emails have the classification prepended to the subject line:

• [cold_outreach] Quick question about your product
• [newsletter] Weekly Digest #42
• [spam] You've won a prize!
• [legitimate] Invoice #1234
• [unknown] Hello

This lets you set up rules in your upstream email provider (Gmail, Outlook, etc.) to automatically sort, label, or filter forwarded emails based on classification.

Configuration

The send_email binding is already configured in wrangler.toml:

[[send_email]]
name = "SEND_EMAIL"

No API keys or external accounts are required. The binding uses Cloudflare Email Routing to send the message.

Requirements

• Your domain must have Cloudflare Email Routing enabled
• The destination email address must be a verified Email Routing destination address in Cloudflare

Immediate vs. Deferred Forwarding

Chatterbox3000 handles two forwarding paths:

Immediate (in email handler)

When an email arrives from an allowed sender with auto-forward enabled, the worker calls message.forward(destination) directly in the email event handler. This is the most efficient path.

Deferred (on manual approval)

When you approve a queued email from the Chrome extension, the worker uses the send_email binding to send a new message to your destination. This works because send_email can be called from any Worker handler, unlike message.forward() which only works in the email event.

Customization

The forwarding logic is in worker/src/services/forwarder.ts. You can customize the MIME message format, headers, or subject prefix there.