const nodemailer = require('nodemailer');
const xoauth2 = require('xoauth2');

// create reusable transporter object using the default SMTP transport
let transporter = nodemailer.createTransport( {
        service: 'gmail',
        xoauth2: xoauth2.createXOAuth2Generator({
            user: 'me@myDomain.com',
            clientid: 'blahblahblah.apps.googleusercontent.com',
            clientSecret: 'k33p-gUeSsINg',
            refreshToken: '123BritneyIsTheBest'
        }),
        tls: {
            rejectUnauthorized: false
        }
    } );

// setup email data with unicode symbols
let mailOptions = {
    from: 'me@myDomain.com',
    to: 'me@yahoo.com',
    subject: 'Hello there Google API...',
    text: 'Hello Google API',
    html: '<b>Hello Google API</b>'
};

// send mail with defined transport object
transporter.sendMail(mailOptions, (error, info) => {
    if (error) {
        return console.log(error);
    }
    console.log('Message sent: ', info.messageId);
});

{
    Error: Mail command failed: 530-5.5.1 Authentication Required. Learn more at 530 5.5.1  https://support.google.com/mail/?p=WantAuthError l24sm4075119ywk.21 - gsmtp
    at SMTPConnection._formatError (C:abcindex.js:591:19)
    at SMTPConnection._actionMAIL (C:abcindex.js:1350:34)
    at SMTPConnection._responseActions.push.str (C:abcindex.js:840:18)
    at SMTPConnection._processResponse (C:abcindex.js:747:20)
    at SMTPConnection._onData (C:abcindex.js:543:14)
    at TLSSocket._socket.on.chunk (C:abcindex.js:495:47)
    at emitOne (events.js:116:13)
    at TLSSocket.emit (events.js:211:7)
    at addChunk (_stream_readable.js:263:12)
    at readableAddChunk (_stream_readable.js:250:11)
    code: 'EENVELOPE',
    response: '530-5.5.1 Authentication Required. Learn more atn530 5.5.1  https://support.google.com/mail/?p=WantAuthError l24sm4075119ywk.21 - gsmtp',
    responseCode: 530,
    command: 'MAIL FROM'
}

const nodemailer = require('nodemailer');

// create reusable transporter object using the default SMTP transport
let transporter = nodemailer.createTransport( {
    host: 'smtp.gmail.com',
    port: 587,
    secure: false,
    auth: {
        user: 'me@myDomain.com',
        pass: 'Seriously?'
    }
});

... all the rest is the same, removed for brevity...