Nodemailer: oauth gmail error: { [Error: unauthorized_client] code: 'EAUTH' }

[connor11528]

I have login with google oauth set up. I pasted in the accessToken field from what got returned from login with google. I cannot get past this error { [Error: unauthorized_client] code: 'EAUTH' }.

var express = require('express'),
    nodemailer = require('nodemailer'),
    xoauth2 = require('xoauth2'),
    router = express.Router();

// create reusable transporter object using the default SMTP transport
var transporter = nodemailer.createTransport({
    service: 'gmail',
    auth: {
        xoauth2: xoauth2.createXOAuth2Generator({
            user: "[email protected]",
            clientId: '925......4cui6indku1jgr7g7kpg6.apps.googleusercontent.com',
            clientSecret: "Y1l..........N7xkKd1x",
            refreshToken: "1/LFVq94wxy6uWMP............QqEWxIgOrJDtdun6zK6XiATCKT",
            accessToken: 'eyJ0eXAiOiJKV....................Zxd4uAPJlZqAdJwcHO3prmVSOtTo4PvEXkzhFJJo'
        })
    }
});

/*

 |--------------------------------------------------------------------------
 | POST /sendEmails
 |--------------------------------------------------------------------------
 */
 router.post('/sendToList', function(req, res){
    console.log(req.body);

    // setup e-mail data with unicode symbols
    var mailOptions = {
        from: '[email protected]', // sender address
        to: '[email protected], [email protected]', // list of receivers
        subject: 'Hello ✔', // Subject line
        text: 'Hello world 🐴', // plaintext body
        html: '<b>Hello world 🐴</b>' // html body
    };

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

 });

 module.exports = router;

[andris9]

Can't help much here, Gmail is really picky. Sometimes the client needs to be re-authorized, sometimes the correct scope ("https://mail.google.com/") is missing. Nodemailer just passes on the access token to Gmail as it is, or generates next one using the refresh token but does not modify any permissions etc.

[connor11528]

Mixed blessing, glad gmail has such good security but a pain for developers!

[ferchichi01]

Hi @connor11528 did you fix the issue

[AdamCraven]

For anyone having "unauthorized_client" issues whilst the following apply:

Using a service account
Have a google suite account attached
Have followed all the 2 leg instructions at: https://nodemailer.com/smtp/oauth2/#oauth-2lo
I finally solved it following the documentation here: https://developers.google.com/identity/protocols/OAuth2ServiceAccount#delegatingauthority

In essence going to
https://admin.google.com/yourgsuitedomain.com/ManageOauthClients
Adding a client id (from service account) and scope: https://mail.google.com/ (final slash important)

Emails started working after that.

[gyoon-dev]

@AdamCraven

Thank you for the message above.
I have been trouble shooting the crap out of the 2LO OAuth method for sending gmail through nodemailer. (the less secure, and 3LO methods work, but for easiest replication, I am trying to get the 2LO method to work)

I noticed that you have a G Suite account attached - my setup is through Firebase (and I am running the nodemailer code on Firebase Cloud Functions with a service account attached to a Firebase project) and am wondering if my woes are due to the fact that I do not have a G Suite account.

Thanks for any additional info you might have!

[gyoon-dev]

I was able to try signing up for G Suite for the domain linked to our Firebase web project and this seems to solve the issue.
Thank you again for the tip above!