Transactional Email

Send transactional email via the Cloudflare Email Service send_email binding (EMAIL). Pair with Email Worker Inbox for the receive side.

API ReferenceCopy Anchor Link

POST /sendCopy Anchor Link

Send an email. Provide text and/or html body content.

to string (required)

Recipient email address.

subject string (required)

Subject line.

text string (optional)

Plain-text body (at least one of text or html required).

html string (optional)

HTML body (at least one of text or html required).

Example RequestCopy Anchor Link

curl -X POST "https://your-worker.workers.dev/send" \
  -H "Content-Type: application/json" \
  -d '{"to":"[email protected]","subject":"Welcome","text":"Thanks for signing up."}'

Success ResponseCopy Anchor Link

{
  "sent": true,
  "to": "[email protected]",
  "subject": "Welcome",
  "messageId": "..."
}

Error CodesCopy Anchor Link

• 400 - Invalid to, subject, body, or JSON (INVALID_TO, INVALID_SUBJECT, MISSING_BODY, INVALID_BODY)
• 502 - Email send failure (SEND_ERROR)

Use CasesCopy Anchor Link

• Learn the Email Sending / send_email binding
• Transactional welcome, reset, and notification emails
• Restrict destinations with destination_address during demos
• Pair with Email Worker Inbox for end-to-end mail experiments

LimitationsCopy Anchor Link

• Requires onboarding a sending domain (wrangler email sending enable)
• FROM_EMAIL must be on that domain
• Optional destination_address on the binding can lock recipients for demos
• No queueing or retry UI in this minimal experiment

DeploymentCopy Anchor Link

curl -X POST "https://your-worker.workers.dev/send" \
  -H "Content-Type: application/json" \
  -d '{"to":"[email protected]","subject":"Welcome","text":"Thanks for signing up."}'

Local DevelopmentCopy Anchor Link

cd apps/experiments/transactional-email
npm install
npm run dev

curl -X POST "http://localhost:8787/send" \
  -H "Content-Type: application/json" \
  -d '{"to":"[email protected]","subject":"Welcome","text":"Thanks for signing up."}'

ConfigurationCopy Anchor Link

wrangler.json declares:

• send_email binding EMAIL (optional destination_address)
• Var FROM_EMAIL

Cloudflare Features UsedCopy Anchor Link

• Workers - Edge compute runtime
• Email Sending - send_email binding for outbound mail