Send emails with Vercel

Use OpenSend from Vercel Serverless Functions, Next.js Route Handlers, or Server Actions. Keep the API key in Vercel project environment variables.

Raw markdown

Environment variables

Set these in the Vercel dashboard or with the Vercel CLI:

bash

OPENSEND_API_KEY=os_your_api_key
OPENSEND_BASE_URL=https://opensend.namuh.co

Use your self-hosted OpenSend origin for OPENSEND_BASE_URL only when applicable.

Next.js on Vercel

The Next.js guide is the recommended starting point. It keeps OpenSend calls in server-only code and returns only the queued email ID to the browser.

Standalone serverless function

import { Opensend } from "opensend";

const opensend = new Opensend(process.env.OPENSEND_API_KEY, {
  baseUrl: process.env.OPENSEND_BASE_URL,
});

export async function POST(request: Request) {
  const { email } = (await request.json()) as { email?: string };
  if (!email) {
    return Response.json({ error: "email is required" }, { status: 400 });
  }

  const { data, error } = await opensend.emails.send({
    from: "OpenSend <onboarding@updates.example.com>",
    to: email,
    subject: "Hello from Vercel",
    html: "<p>Vercel queued this email with OpenSend.</p>",
  });

  if (error) {
    return Response.json(
      { error: error.message, code: error.code },
      { status: error.statusCode },
    );
  }

  return Response.json({ id: data.id });
}

Notes

Do not expose the key with NEXT_PUBLIC_.
Use runtime = "nodejs" when rendering React Email components or importing Node-only dependencies.
Vercel may retry failed invocations depending on the trigger; use idempotency keys for duplicate-sensitive sends.