How to Send Email on Vercel

On Vercel you send email through an HTTP API, not SMTP. Vercel runs your code in serverless and edge functions, and those runtimes are built around short-lived HTTP request handling, not long-held TCP sockets. The Edge runtime in particular has no Node net module, so an SMTP library cannot even open a connection. An HTTPS request to an email API fits the model cleanly. Here is the Next.js setup.

Why does SMTP not work well on Vercel?

Serverless functions are designed to start fast, handle a request, and shut down. Holding open an SMTP connection (with its multi-step handshake) cuts against that, and the function may be frozen or torn down mid-conversation. The Edge runtime is stricter still: it runs a web-standard environment without Node's networking modules, so libraries like Nodemailer that depend on net and tls will not run there at all. Sending over HTTPS sidesteps both problems, because fetch is exactly what these runtimes are built to do.

How do you send email from a Next.js Route Handler?

Create a Route Handler at app/api/send/route.ts. It reads the API key from an environment variable and calls the email API. Using the Bird Node SDK:

// app/api/send/route.ts
import { BirdClient } from "@messagebird/sdk";

export const runtime = "nodejs";

const bird = new BirdClient({ apiKey: process.env.BIRD_API_KEY! });

export async function POST(request: Request) {
  const { to } = await request.json();

  const { data, error } = await bird.email
    .send({
      from: "you@yourdomain.com",
      to: [to ?? "delivered@bird.dev"],
      subject: "Hello from Node",
      html: "<p>It works.</p>",
    })
    .safe();

  if (error) {
    return Response.json({ error: error.message }, { status: 502 });
  }

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

Set BIRD_API_KEY in the Vercel project's environment variables so it is available at runtime and never committed. The delivered@bird.dev sandbox address always accepts mail, which makes the first deploy easy to verify.

Edge runtime or Node runtime?

The export const runtime line picks which one runs your handler. Because the SDK and fetch both work in either, you can choose based on your other needs:

If you only call an HTTP API, the Edge runtime gives you faster cold starts. If you depend on a Node-only package elsewhere in the handler, stay on Node. Either way the email send is the same fetch-based call.

Send it with Bird

The handler above already uses the canonical snippet. The shape is the same anywhere you run JavaScript:

import { BirdClient } from "@messagebird/sdk";

const bird = new BirdClient({ apiKey: process.env.BIRD_API_KEY! });

const { data, error } = await bird.email
  .send({
    from: "you@yourdomain.com",
    to: ["delivered@bird.dev"],
    subject: "Hello from Node",
    html: "<p>It works.</p>",
  })
  .safe();

If you build your email bodies as components, React Email renders them to the HTML this call expects. For the wider picture of where email code belongs, see sending email with JavaScript.

FAQ

Can I use Nodemailer on Vercel?

On the Node runtime it will load, but holding an SMTP connection open is unreliable on short-lived serverless functions. On the Edge runtime it cannot run, because there is no Node net module. An HTTP API avoids both issues.

Where do I store my API key on Vercel?

In the project's environment variables, set in the Vercel dashboard or CLI. The handler reads it with process.env, so it stays on the server and out of your repository.

Edge or Node runtime for sending email?

Either works for an HTTP API call. Edge has faster cold starts; Node is required if your handler also uses Node-only packages.

Vercel and an HTTP email API are a natural pair. The email product overview and the sending email guide cover the rest of the surface.