Send email with Astro

An API route in a mostly static site, sending on demand.

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 type { APIRoute } from "astro";
import { Sending } from "sending-sdk";
 
const sending = new Sending({ apiKey: import.meta.env.SENDING_API_KEY });
 
export const POST: APIRoute = async ({ 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 new Response(JSON.stringify(res), { status: 202 });
};

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 Astro

The route needs output: 'server' or a hybrid config with prerender disabled: a fully static build has nowhere to run this.

The thing that catches people

Only variables prefixed with PUBLIC_ are exposed to the client, but a static build inlines whatever it can reach. Keep the send in an API route rather than in a component's frontmatter.

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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