Send transactional mail from a Cloudflare Worker binding

For a Worker deployment, use Cloudflare’s native email binding after domain onboarding. Add the binding to the existing Wrangler configuration; do not replace the rest of the application configuration:

{ "send_email": [{ "name": "EMAIL" }] }

Call the binding from an authorized application action

This is a handler excerpt, not a public unauthenticated send endpoint. Supply the approved sender and controlled recipient, and authorize the triggering application operation before calling it:

const result = await env.EMAIL.send({
  from: { email: approvedSender, name: "Application" },
  to: controlledRecipient,
  subject: "Cloudflare controlled test",
  text: "A message from the onboarded application domain.",
});
console.log({ messageId: result.messageId });

The Workers API reference defines this builder and result. REST API field names and response shape differ; do not mix its address/snake-case model into a binding example.

Verify and handle failures

Persist the intended send and returned identity, then check available sending activity and the controlled inbox. Handle the documented sender-verification, validation, and rate-limit errors at their actual boundary.

An exception/timeout may require investigation before retrying. A successful binding call is not a blanket inbox-placement guarantee. Respect the transactional-only channel and its account/domain limits.

For a platform-independent application path, use MailKite’s sending SDK with its own verified domain; a Cloudflare binding is not automatically a MailKite client.