Authentication Bug With Gmail Api Oauth2.

error.log

error: Error: Mail command failed: 530-5.5.1 Authentication Required. Learn more at
530 5.5.1  https://support.google.com/mail/?p=WantAuthError m17sm5782308pff.170 - gsmtp
    at SMTPConnection._formatError (C:\Users\JITPOMI\code\chat-app\chat-s\node_modules\feathers-mailer\node_modules\nodemailer\lib\smtp-connection\index.js:605:19)
    at SMTPConnection._actionMAIL (C:\Users\JITPOMI\code\chat-app\chat-s\node_modules\feathers-mailer\node_modules\nodemailer\lib\smtp-connection\index.js:1370:34)
    at SMTPConnection._responseActions.push.str (C:\Users\JITPOMI\code\chat-app\chat-s\node_modules\feathers-mailer\node_modules\nodemailer\lib\smtp-connection\index.js:857:18)
    at SMTPConnection._processResponse (C:\Users\JITPOMI\code\chat-app\chat-s\node_modules\feathers-mailer\node_modules\nodemailer\lib\smtp-connection\index.js:764:20)
    at SMTPConnection._onData (C:\Users\JITPOMI\code\chat-app\chat-s\node_modules\feathers-mailer\node_modules\nodemailer\lib\smtp-connection\index.js:570:14)
    at TLSSocket._socket.on.chunk (C:\Users\JITPOMI\code\chat-app\chat-s\node_modules\feathers-mailer\node_modules\nodemailer\lib\smtp-connection\index.js:522:47)
    at TLSSocket.emit (events.js:189:13)
    at TLSSocket.EventEmitter.emit (domain.js:441:20)
    at addChunk (_stream_readable.js:288:12)
    at readableAddChunk (_stream_readable.js:269:11)
    at TLSSocket.Readable.push (_stream_readable.js:224:10)
    at TLSWrap.onStreamRead [as onread] (internal/stream_base_commons.js:145:17)
error: Unhandled Rejection at: Promise  {"meta":[{},{"code":"EENVELOPE","response":"530-5.5.1 Authentication Required. Learn more at\n530 5.5.1  https://support.google.com/mail/?p=WantAuthError m17sm5782308pff.170 - gsmtp","responseCode":530,"command":"MAIL FROM"}]}

feathers-mailer.js

const Proto = require('uberproto');
const Mailer = require('nodemailer');
const debug = require('debug')('feathers-mailer');

class Service {
  constructor (transport, defaults) {
    debug('constructor', transport);

    if (!transport) {
      throw new Error('feathers-mailer: constructor `transport` must be provided');
    }

    this.transporter = Mailer.createTransport(transport, defaults);
  }

  extend (obj) {
    return Proto.extend(obj, this);
  }

  create (body, params) {
    debug('create', body, params);

    // TODO maybe body should be text/html field
    // and params is rest of options

    // https://github.com/nodemailer/nodemailer#set-up-smtp says:
    // If callback argument is not set then the method returns a Promise object.
    return this.transporter.sendMail(body);
  }
}

module.exports = function init (transport, defaults) {
  return new Service(transport, defaults);
};

module.exports.Service = Service;

mailer.service.js

// Initializes the `mailer` service on path `/mailer`
// mailer is an email sending service

/* eslint-disable no-console */

const hooks = require('./mailer.hooks');
const Mailer = require('feathers-mailer');
const { google } = require('googleapis');

const OAuth2 = google.auth.OAuth2;

module.exports = async function(app) {
  try {
    const { user, clientId, clientSecret, refreshToken } = app.get('xoauth2');

    /**
     * Create a new OAuth2 client with the configured keys.
     */
    const oauth2Client = new OAuth2(
      clientId, // ClientID
      clientSecret, // Client Secret
      'https://developers.google.com/oauthplayground' // Redirect URL
    );

    /**
     * Access tokens expire.
     * This library will automatically use a refresh token to obtain a new access token if it is about to expire.
     */

    oauth2Client.setCredentials({
      refresh_token: refreshToken,
    });

    // const tokens = await oauth2Client.refreshAccessToken();
    // const accessToken = tokens.credentials.access_token;

    const {res} = await oauth2Client.getAccessToken();

    const { access_token, expiry_date } = res.data;

    const accessToken = access_token;
    const expires=expiry_date;

    console.log('access token: ',accessToken, ' expires: ',expires);

    app.use(
      '/mailer',
      Mailer({
        host: 'smtp.gmail.com',
        port: 465,
        secure: true,
        service: 'Gmail',
        auth: {
          type: 'OAuth2',
          user,
          clientId,
          clientSecret,
          refreshToken,
          accessToken,
          expires
        },

        tls: {
          rejectUnauthorized: false, // do away with sendmail error : self signed certificate
        },
      })
    );
    // Get our initialized service so that we can register hooks and filters
    const service = app.service('mailer');

    service.hooks(hooks);
  } catch (err) {
    console.log('Error: ', err.message);
  }
};

Hi. I am implementing a emailer service with nodemailer and googleapi, making use of their gmailAPI and oauthplayground as authorised redirect url... but I am getting the bug in error.log above. Kindly help me fix it.

Thanks