How to Send Emails from a Custom Domain in Node.js (Express.js) with Resend

Introduction

Sending emails from a custom domain like [email protected] is essential for maintaining a professional image and ensuring email deliverability. In this guide, we'll walk through how to send emails in an Express.js project using Resend, a simple and developer-friendly email API.

Prerequisites

Before we start, ensure you have:

• A Resend account (sign up here).

• A verified domain on Resend.

• An Express.js project set up.

• Your Resend API key.

Step 1: Install Resend and Express.js

First, install the required dependencies in your Express.js project:

npm install express resend dotenv cors body-parser

Then, create a .env file to store your API key:

API_RESEND_NOREPLY=your_resend_api_key_here

Step 2: Set Up the Email Sending Function

Create a utility function to send emails using Resend. In utils/email.js:

import { Resend } from "resend";
import dotenv from "dotenv";

dotenv.config();
const resend = new Resend(process.env.API_RESEND_NOREPLY);

export async function sendMail({ to, subject, html }) {
  try {
    const response = await resend.emails.send({
      from: "[email protected]",
      to,
      subject,
      html,
    });
    return response;
  } catch (error) {
    console.error("Email sending error:", error);
    throw error;
  }
}

Step 3: Create an API Endpoint in Express.js

In server.js, set up an Express.js server with an endpoint to send emails:

import express from "express";
import cors from "cors";
import bodyParser from "body-parser";
import { sendMail } from "./utils/email.js";

dotenv.config();
const app = express();
const PORT = process.env.PORT || 5000;

app.use(cors());
app.use(bodyParser.json());

app.post("/send-email", async (req, res) => {
  const { to, subject, html } = req.body;
  if (!to || !subject || !html) {
    return res.status(400).json({ error: "Missing required fields" });
  }

  try {
    const emailResponse = await sendMail({ to, subject, html });
    return res.status(200).json({ success: true, emailResponse });
  } catch (error) {
    return res.status(500).json({ error: "Failed to send email" });
  }
});

app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
});

Step 4: Test the Email API

You can test your email-sending functionality using Postman or a simple fetch request in a frontend application:

fetch("http://localhost:5000/send-email", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    to: "[email protected]",
    subject: "Welcome!",
    html: "<p>Hello, welcome to our platform!</p>",
  }),
})
  .then((res) => res.json())
  .then((data) => console.log(data));

Conclusion

Using Resend with Express.js, you can easily send emails from your custom domain in a few simple steps. By following this guide, you ensure better deliverability and a professional email-sending setup. 🚀

If you encounter issues, check Resend’s documentation or verify your domain settings. Happy coding!

FAQs

1. Can I send bulk emails using Resend?
Yes, but it's recommended to follow best practices for email deliverability.

2. How do I track email opens and clicks?
Resend provides analytics to track email performance.

3. Is Resend free to use?
Resend offers a free plan with limited emails per month. Check their pricing for details.

4. How do I avoid spam filters?
Ensure proper SPF, DKIM, and DMARC records are set up in your DNS.

5. Can I use Resend with other frameworks?
Yes! Resend works with Node.js, Express.js, and other backends like Next.js.