Send email with SvelteKit

A form action or a +server endpoint, with the key from $env/static/private.

You need a verified sending domain and an API key from Settings › API Keys. If neither exists yet, the quickstart covers both in a couple of minutes.

Install

npm i sending-sdk

Send

import { json } from "@sveltejs/kit";
import { SENDING_API_KEY } from "$env/static/private";
import { Sending } from "sending-sdk";
 
const sending = new Sending({ apiKey: SENDING_API_KEY });
 
export async function POST({ request }) {
  const { email, userId } = await request.json();
  const res = await sending.emails.send({
    from: "Acme <[email protected]>",
    to: email,
    subject: "Welcome",
    html: "<p>You're in.</p>",
    idempotencyKey: `welcome-${userId}`,
  });
  return json(res);
}

A successful call answers 202 with the message id: accepted and queued, not yet delivered. Delivery, opens, bounces and complaints arrive later, on webhooks or in the dashboard.

What changes in SvelteKit

$env/static/private is checked at build time: importing it from client code is a build error rather than a leaked key at runtime.

The thing that catches people

On the edge adapters use $env/dynamic/private instead: static values are inlined at build time and a platform secret set afterwards will not appear.

Next

  • All the fields: cc and bcc, reply-to, attachments, templates, scheduling.
  • Webhooks: delivery, bounce and complaint events, signed with HMAC.
  • Domains: SPF, DKIM and MAIL FROM, and why sending is refused until they are in place.
  • MCP: the same operations as tools, when the one writing the code is an agent.

Nearby: JavaScript and TypeScript

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