Nodemail to send mail for firebase app with service account - firebase

Question

I get the following message when trying to send mail with Nodemailer :
'535-5.7.8 Username and Password not accepted.
Learn more at\n535 5.7.8 https://support.google.com/mail/?p=BadCredentials y42sm13399804wrc.51 - gsmtp',
responseCode: 535,
command: 'AUTH XOAUTH2' }
I am using a service account from a firebase project, and have granted access to the GMail API. But the nodemailer docs for 2LO is really scarce so I wonder if anyone could help me find if I use the correct credentials ?
user (functions.config().gmail.user) : myfirebaseproject#appspot.gserviceaccount.com
-
function sendContactMail(contactName, contactEmail, contactDate, contactText) {
// Create transport
let transporter = nodemailer.createTransport({
host: 'smtp.gmail.com',
port: 465,
secure: true,
auth: {
type: 'OAuth2',
user: functions.config().gmail.user,
serviceClient: functions.config().gmail.client_id,
privateKey: functions.config().gmail.private_key
//accessToken: 'ya29.Xx_XX0xxxxx-xX0X0XxXXxXxXXXxX0x',
//expires: 1484314697598
}
});
// Mail Options
let mailOptions = {
from: `"${APP_NAME}" <${SENDER}>`,
replyTo: `${contactEmail}`,
to: 'recipient#gmail.com',
subject: `Nouveau contact photo de ${contactName}`,
html: `Nom : ${contactName}<br/>
Email : ${contactEmail}<br/>
Date du mariage : ${contactDate}<br/>
Message : ${contactText}`,
disableFileAccess: true,
disableUrlAccess:true
};
// Send Mail
return transporter.sendMail(mailOptions);
}

Answer 1

Has your account two steps authentication enabled? In that case generate an app password on https://myaccount.google.com/apppasswords and use it instead of your normal password:
const mailTransport = nodemailer.createTransport(
`smtps://user#gmail.com:generatedAppPassword#smtp.gmail.com`);

Answer 2

I have Cloud Function with this code and it's work fine. Try this
mailTransport = nodemailer.createTransport({
service: 'Gmail',
auth: {
user: ${email},
pass: ${password}
}
});