var nodemailer = require("nodemailer");
var from = "xxx@gmail.com";

// create reusable transport method (opens pool of SMTP connections)
let poolConfig = {
pool: true,
host: 'smtp.gmail.com',
port: 465,
    secure: true, // use TLS
    auth: {
        user: from,
        pass: "xxx"
    }
};
var smtpTransport = nodemailer.createTransport(poolConfig);

let message = {
    from: from, // listed in rfc822 message header
    to: 'xxx@gmail.com', // listed in rfc822 message header
    subject: 'Message title',
    text: 'Plaintext version of the message',
    html: '<p>HTML version of the message</p>'
};
smtpTransport.sendMail(message, function(){
    console.log("Success!");
});