How to Send Emails in Node.js (2026 Guide)

Why Send Emails from Node.js?

Almost every web application needs to send emails — password resets, order confirmations, notifications, and more. Node.js is one of the most popular server-side runtimes, and sending emails from it should be simple.

There are two main approaches:

• REST API — Make HTTP requests to an email service (recommended)
• SMTP — Use a library like Nodemailer to connect via SMTP

Method 1: REST API (Recommended)

The simplest way to send emails from Node.js is using a REST API. No SMTP configuration, no connection pooling — just a single HTTP request.

// Using fetch (built into Node.js 18+)
const response = await fetch('https://api.unosend.co/v1/emails', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer un_your_api_key',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    from: 'hello@yourdomain.com',
    to: 'user@example.com',
    subject: 'Welcome to our app!',
    html: '<h1>Welcome!</h1><p>Thanks for signing up.</p>',
  }),
});

const data = await response.json();
console.log('Email sent:', data.id);

With the Unosend SDK

For a better developer experience, use the official SDK:

npm install @unosend/node

import { Unosend } from '@unosend/node';

const unosend = new Unosend('un_your_api_key');

const { data, error } = await unosend.emails.send({
  from: 'hello@yourdomain.com',
  to: 'user@example.com',
  subject: 'Welcome!',
  html: '<h1>Welcome!</h1>',
});

Method 2: SMTP with Nodemailer

If you prefer SMTP, you can use Nodemailer with any SMTP provider:

import nodemailer from 'nodemailer';

const transporter = nodemailer.createTransport({
  host: 'smtp.unosend.co',
  port: 587,
  secure: false,
  auth: {
    user: 'apikey',
    pass: 'un_your_api_key',
  },
});

await transporter.sendMail({
  from: 'hello@yourdomain.com',
  to: 'user@example.com',
  subject: 'Hello from Node.js',
  html: '<p>Sent via SMTP</p>',
});

Express.js Example

import express from 'express';
import { Unosend } from '@unosend/node';

const app = express();
const unosend = new Unosend(process.env.UNOSEND_API_KEY);

app.post('/api/contact', async (req, res) => {
  const { name, email, message } = req.body;

  const { error } = await unosend.emails.send({
    from: 'contact@yourdomain.com',
    to: 'team@yourdomain.com',
    subject: `Contact form: ${name}`,
    html: `<p>From: ${name} (${email})</p><p>${message}</p>`,
  });

  if (error) return res.status(500).json({ error });
  res.json({ success: true });
});

Next.js Server Action

'use server'
import { Unosend } from '@unosend/node';

const unosend = new Unosend(process.env.UNOSEND_API_KEY!);

export async function sendWelcomeEmail(email: string, name: string) {
  const { error } = await unosend.emails.send({
    from: 'welcome@yourdomain.com',
    to: email,
    subject: `Welcome, ${name}!`,
    html: `<h1>Welcome to our app, ${name}!</h1>`,
  });

  if (error) throw new Error('Failed to send email');
  return { success: true };
}

Production Best Practices

• Never hardcode API keys — Use environment variables
• Handle errors gracefully — Wrap send calls in try/catch
• Use webhooks — Track delivery, opens, clicks, and bounces
• Verify your domain — Set up SPF, DKIM, and DMARC for better deliverability
• Rate limit your sends — Respect API rate limits and implement retry logic

Conclusion

Sending emails from Node.js takes just a few lines of code with a REST API. Start with 5,000 free emails/month on Unosend and scale from there.