Install nodemailer

    npm i nodemailer

Send Mail - test_mail.js

    var nodemailer = require('nodemailer');
    var transporter = nodemailer.createTransport({
        service: 'gmail',
        auth: {
        user: 'youremail@gmail.com',
        pass: 'yourpassword'
        }
    });
    
    var mailOptions = {
        from: 'youremail@gmail.com',
        to: 'nareshkumarh@live.com',
        subject: 'Reg - Activate User Account',
        text: 'Thanks for Signing Up. Activation Code: 1234 !'
    };
    
    transporter.sendMail(mailOptions, function(error, info){
        if (error) {
        console.log(error);
        } else {
        console.log('Email sent: ' + info.response);
        }
    });

Test

• node test_mail.js

Note: Gmail Settings

• Turn On - Less Secure app Access ( or generate App Password in gmail)
• Unlock Captcha - https://accounts.google.com/DisplayUnlockCaptcha
• Turn off after testing mail api.