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Runtime API

Background

An EmailEvent is the event type to programmatically process your emails with a Worker. You can reject, forward, or drop emails according to the logic you construct in your Worker.

Syntax: Service Worker

EmailEvent can be handled in Workers functions written using the Service Worker syntax by attaching to the email event with addEventListener:

addEventListener("email", (event) => {
  event.message.forward("<YOUR_EMAIL>");
});

Properties

Syntax: ES modules

EmailEvent can be handled in Workers functions written using the ES modules format by adding an email function to your module's exported handlers:

export default {
  async email(message, env, ctx) {
    message.forward("<YOUR_EMAIL>");
  },
};

Parameters

  • message EmailMessage

  • env object

    • An object containing the bindings associated with your Worker using ES modules format, such as KV namespaces and Durable Objects.

  • ctx object

    • An object containing the context associated with your Worker using ES modules format. Currently, this object just contains the waitUntil function.

EmailMessage definition

 interface EmailMessage<Body = unknown> {
  readonly from: string;
  readonly to: string;
  readonly headers: Headers;
  readonly raw: ReadableStream;
  readonly rawSize: number;


  public constructor(from: string, to: string, raw: ReadableStream | string);


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

  • from string

    • Envelope From attribute of the email message.

  • to string

    • Envelope To attribute of the email message.

  • headers Headers

  • raw ReadableStream

    • Stream of the email message content.

  • rawSize number

    • Size of the email message content.

  • setReject(reasonstring) : void

    • Reject this email message by returning a permanent SMTP error back to the connecting client, including the given reason.

  • forward(rcptTostring, headersHeadersoptional) : Promise

    • Forward this email message to a verified destination address of the account. If you want, you can add extra headers to the email message. Only X-* headers are allowed.
    • When the promise resolves, the message is confirmed to be forwarded to a verified destination address.

  • reply(messageEmailMessage) : Promise

    • Reply to the sender of this email message with a new EmailMessage object.
    • When the promise resolves, the message is confirmed to be replied.
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