Sending Email with Node.js

In order to send an email, you need to use Simple Mail Transfer Protocol (SMTP). SMTP is part of the application layer of the TCP/IP Protocol. There are two choices to send the email via Node.js:

1. Use node.js send email via SMTP to Email Server directly
2. Use node.js send HTTP request to Email Delivery Service. It then sends email to Email Server via SMTP to Email Server.

The advantage of the second choice is you can choose beautiful style without write your own HTML & CSS code. It helps reduce time to code and easy to send email.

Nodemailer

Nodemailer is a module for node.js applications to allow email sending.

npm install nodemailer

const express = require('express');
const exphbs = require('express-handlebars');
const nodemailer = require('nodemailer');
const path = require('path');
require('dotenv').config({ path: './.env' });

const app = express();

// template engine setup
app.engine('handlebars', exphbs());
app.set('view engine', 'handlebars');

// static folder
app.use('/public', express.static(path.join(__dirname, 'public')));

// body parser middleware (body parser is deprecated for express v 4.16 +)
app.use(express.urlencoded({ extended: false }));
app.use(express.json());

app.get('/', (req, res) => {
  res.render('contact', { layout: false });
});

app.post('/send-email', async (req, res) => {
  // create reusable transporter object using the default SMTP transport
  let transporter = nodemailer.createTransport({
    service: 'hotmail',
    auth: {
      user: process.env.EMAIL_USERNAME,
      pass: process.env.EMAIL_PASSWORD,
    },
    from: process.env.EMAIL_USERNAME,
  });

  const info = {
    from: `Chitsanupong <${process.env.EMAIL_USERNAME}>`,
    to: 'c.tangvasinkul@gmail.com',
    subject: 'Sending Email with Node.js',
    text: 'Hello Chitsanupong!', // plain text body
    html: `<b>Hello Chitsanupong!</b>`,
    attachments: [
      {
        filename: 'logo.jpg',
        path: './logo.jpg',
      },
    ],
  };

  // send mail with defined transport object
  await transporter.sendMail(info, (err, info) => {
    if (err) {
      res.send({ error: err }).status(500);
    } else {
      console.log('Sent: ' + info.response);
      res.send({ message: 'OK' }).status(200);
    }
  });
});

app.listen(4000, () => console.log('Listening on Port 4000'));

To send e-mail via g-mail, you need to turn on the less secure app access in your google account. Then, change service name.

let transporter = nodemailer.createTransport({
  service: 'gmail',
  auth: {
    user: process.env.GMAIL_USERNAME,
    pass: process.env.GMAIL_PASSWORD,
  },
  from: process.env.EMAIL_USERNAME,
});

Deploy to Google Cloud

1. Create a new project and go to App Engine section
2. Install Google Cloud SDK
3. Run gcloud init to initialize and sign in
4. Create app.yaml file in NodeJS app which you can see documentation here
5. If you encounter "[7] Access Not Configured." Error, you need to disable Cloud Build API and enable it again.
6. GCP will use server.js file as a main JavaScript file
7. Run gcloud app deploy to deploy
8. Open your application link to see the result
9. Run gcloud app logs tail -s default to show all logs

Handling Error

if you encounter this error:

Error: Server Error

The server encountered an error and could not complete your request.

Please try again in 30 seconds.

You need to check your package.json and make sure that the start script is true in case main JavaScript file is not the server.js. For example, if your main JavaScript file is app.js instead of server.js, you need to change start script to "start": "node app.js".