# `Letterbox.Ingress.Relay`
[🔗](https://github.com/hattoriai/letterbox/blob/v0.1.0-rc.0/lib/letterbox/ingress/relay.ex#L1)

Raw emails, posted as they are by whatever has them: a mail server's
pipe (Postfix, Exim), a Cloudflare Email Worker, a script.

    config :letterbox, ingresses: [relay: [token: "a long random token"]]

A request is a `POST` to its route (`/inbound/webhooks/relay`, as
`mix letterbox.install` writes it) with the email as its body
(`Content-Type: message/rfc822`), and the token as a bearer
(`Authorization: Bearer <token>`) or as the password of basic auth (as
Action Mailbox's relay takes it). Two headers help:

  * `X-Letterbox-Recipients` - the envelope's recipients, separated by
    commas: the addresses the mail server took it for.
  * `X-Letterbox-Id` - an id of the email's, to take it once only when it
    is posted twice.

From Postfix, in `master.cf`:

    letterbox unix - n n - - pipe
      flags=Rq user=mail argv=/usr/bin/curl --fail --data-binary @-
        -H Content-Type:message/rfc822 -H Authorization:Bearer\ <token>
        -H X-Letterbox-Recipients:${recipient}
        https://example.com/inbound/webhooks/relay

From a Cloudflare Email Worker:

    export default {
      async email(message, env) {
        await fetch("https://example.com/inbound/webhooks/relay", {
          method: "POST",
          body: message.raw,
          headers: {
            "content-type": "message/rfc822",
            authorization: `Bearer ${env.LETTERBOX_TOKEN}`,
            "x-letterbox-recipients": message.to
          }
        });
      }
    };

---

*Consult [api-reference.md](api-reference.md) for complete listing*