Node.js + Nodemailer: Sending email with Gmail

server.js

const express = require("express");
const bodyParser = require("body-parser");
const nodemailer = require("nodemailer");

const app = express();

app.use(bodyParser.json());

app.use((req, res, next) => {
  res.setHeader("Access-Control-Allow-Origin", "*");
  res.setHeader(
    "Access-Control-Allow-Methods",
    "OPTIONS, GET, POST, PUT, PATCH, DELETE"
  );
  res.setHeader(
    "Access-Control-Allow-Headers",
    "Content-Type, Authorization, from, size, fields, type"
  );
  next();
});

app.get("/", (req, res, next) => {
  res.send("Well, it works.");
});


/**
 * Send email
 */

app.post('/sendemail', (req, res, next) => {
  const subject = req.body.subject;
  const email = req.body.email;
  const message = req.body.message;

  let smtpTransport = nodemailer.createTransport({
    service: 'gmail',
    host: 'smtp.gmail.com',
    secure: true,
    port: 465,
    auth: {
      user: <[email protected]>,
      pass: <password>
    }
  });

  let mailOptions = {
    from: email, //sender adress
    to: "[email protected]", //receive adress
    subject: `Subject - ${subject}`,
    html: `
    <b>- From: </b> ${email} <br />
    <b>- Subject: </b> ${subject} <br />
    <b>- Message: </b> <br /> <br/> ${message}
    `
  };

  smtpTransport
    .sendMail(mailOptions)
    .then((result) => {
      console.log(result);
      res.status(200).json(result);
    })
    .catch(err => {
      console.log(err);
      res.status(400).json(err);
    })
})

/**
 * Error handler
 */
app.use((error, req, res, next) => {
  const status = error.statusCode || 500;
  const message = error.message;
  const data = error.data;
  res.status(status).json({ message: message, data: data });
});

app.listen(3000, () => {
  console.log("up and running on 3000");
});