Nodemailer error while using gmail in firebase fun

Question

I am using firebase cloud functions. I have the following setup configured. While that is working completely fine on my local machine, It's giving me an issue when run on the servers. I have tried gazillion work arounds on the internet but no luck. What is wrong with this?

'use strict'
const functions = require('firebase-functions');
var admin = require('firebase-admin');
const express = require('express');
const nodemailer = require('nodemailer');
const app = express()

var emailRecepient;
var userName;


const smtpTransport = nodemailer.createTransport({
service: "gmail",
host: 'smtp.gmail.com',
port: 587, // tried enabling and disabling these, but no luck
secure: false, // similar as above
auth: {
  user: '<emailid>',
  pass: '<password>'
    },
        tls: {
        rejectUnauthorized: false
    }
});

var mailOptions = {
  from: 'test <[e-mail]>',
  to: emailRecepient,
  subject: 'Welcome to test',
  text: 'welcome ' + userName + ". did you see the new things?"
};

function sendmail() {
smtpTransport.sendMail(mailOptions, function (error, info) {
    if (error) {
        console.log(error);
    }
    else {
        console.log('Email sent: ' + info.response);
    }
});
};

exports.sendEmails = functions.database.ref('/users/{userID}/credentials').onCreate((snap, context) => {

  const userID = context.params.userID;
  const vals = snap.val()

  userName = vals.name;
  emailRecepient = vals.email;

  smtpTransport.sendMail(mailOptions, function (error, info) {
  if (error) {
      console.log("Error sending email ---- ",error);
  }
  else {
      console.log('Email sent: ' + info.response);
  }
  });

  return true;

});

The error I got on all cases is :

        Error sending email 2 ----  { Error: Invalid login: 534-5.7.14 <https://accounts.google.com/signin/continue?sarp=1&scc=1&plt=AKgnsbsi
    534-5.7.14 qRQLfD9YlFZDsPj7b8QQACro9c41PjhSVo0NZ4i5ZHNlyycFi_FyRp8VdZ_dH5ffWWAABQ
    534-5.7.14 8rH2VcXkyZBFu00-YHJUQNOqL-IqxEsZqbFCwCgk4-bo1ZeDaKTdkEPhwMeIM2geChH8av
    534-5.7.14 0suN293poXFBAk3TzqKMMI34zCvrZlDio-E6JVmTrxyQ-Vn9Ji26LaojCvdm9Bq_4anc4U
    534-5.7.14 SpQrTnR57GNvB0vRX1BihDqKuKiXBJ5bfozV1D1euQq18PZK2m> Please log in via
    534-5.7.14 your web browser and then try again.
    534-5.7.14  Learn more at
    534 5.7.14  https://support.google.com/mail/answer/78754 t2sm3669477iob.7 - gsmtp
        at SMTPConnection._formatError (/user_code/node_modules/nodemailer-smtp-transport/node_modules/smtp-connection/lib/smtp-connection.js:528:15)
        at SMTPConnection._actionAUTHComplete (/user_code/node_modules/nodemailer-smtp-transport/node_modules/smtp-connection/lib/smtp-connection.js:1231:30)
        at SMTPConnection.<anonymous> (/user_code/node_modules/nodemailer-smtp-transport/node_modules/smtp-connection/lib/smtp-connection.js:319:22)
        at SMTPConnection._processResponse (/user_code/node_modules/nodemailer-smtp-transport/node_modules/smtp-connection/lib/smtp-connection.js:669:16)
        at SMTPConnection._onData (/user_code/node_modules/nodemailer-smtp-transport/node_modules/smtp-connection/lib/smtp-connection.js:493:10)
        at emitOne (events.js:96:13)
        at TLSSocket.emit (events.js:188:7)
        at readableAddChunk (_stream_readable.js:176:18)
        at TLSSocket.Readable.push (_stream_readable.js:134:10)
        at TLSWrap.onread (net.js:559:20)
      code: 'EAUTH',
      response: '534-5.7.14 <https://accounts.google.com/signin/continue?sarp=1&scc=1&plt=AKgnsbsi\n534-5.7.14 qRQLfD9YlFZDsPj7b8QQACro9c41PjhSVo0NZ4i5ZHNlyycFi_FyRp8VdZ_dH5ffWWAABQ\n534-5.7.14 8rH2VcXkyZBFu00-YHJUQNOqL-IqxEsZqbFCwCgk4-bo1ZeDaKTdkEPhwMeIM2geChH8av\n534-5.7.14 0suN293poXFBAk3TzqKMMI34zCvrZlDio-E6JVmTrxyQ-Vn9Ji26LaojCvdm9Bq_4anc4U\n534-5.7.14 SpQrTnR57GNvB0vRX1BihDqKuKiXBJ5bfozV1D1euQq18PZK2m> Please log in via\n534-5.7.14 your web browser and then try again.\n534-5.7.14  Learn more at\n534 5.7.14  https://support.google.com/mail/answer/78754 t2sm3669477iob.7 - gsmtp',
      responseCode: 534,
      command: 'AUTH PLAIN' }

I have even turned of the allow secure apps in the google settings. But for some reason this doesn't seem to work. Any help is extremely appreciated.

As advised by Renaud, I tried firebase-samples/email-confirmation and I am having following error :

TypeError: snapshot.changed is not a function
at exports.sendEmailConfirmation.functions.database.ref.onWrite (/user_code/index.js:38:17)
at Object.<anonymous> (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:112:27)
at next (native)
at /user_code/node_modules/firebase-functions/lib/cloud-functions.js:28:71
at __awaiter (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:24:12)
at cloudFunction (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:82:36)
at /var/tmp/worker/worker.js:758:24
at process._tickDomainCallback (internal/process/next_tick.js:135:7)

Cheers

Answer 1

I see it was a long discussion, let me share the code snippets which worked out for me for others with similar issues so it will be easier to figure out.

1) function.ts (it's written in TypeScript)

import * as admin from 'firebase-admin';
import * as functions from 'firebase-functions';
import * as nodemailer from 'nodemailer';

admin.initializeApp();

// I'm taking all these constants as secrets injected dynamically (important when you make `git push`), but you can simply make it as a plaintext.
declare const MAIL_ACCOUNT: string; // Declare mail account secret.
declare const MAIL_HOST: string; // Declare mail account secret.
declare const MAIL_PASSWORD: string; // Declare mail password secret.
declare const MAIL_PORT: number; // Declare mail password secret.

const mailTransport = nodemailer.createTransport({
  host: MAIL_HOST,
  port: MAIL_PORT, // This must be a number, important! Don't make this as a string!!
  auth: {
    user: MAIL_ACCOUNT,
    pass: MAIL_PASSWORD
  }
});

exports.sendMail = functions.https.onRequest(() => {
  const mailOptions = {
    from: 'ME <[e-mail]>',
    to: '[e-mail]',
    subject: `Information Request from ME`,
    html: '<h1>Test</h1>'
  };
  mailTransport
    .sendMail(mailOptions)
    .then(() => {
      return console.log('Mail sent'); // This log will be shown in Firebase Firebase Cloud Functions logs.
    })
    .catch(error => {
      return console.log('Error: ', error); // This error will be shown in Firebase Cloud Functions logs.
    });
});

This said, you should receive an e-mail from [e-mail] to [e-mail], of course modify it for your own needs.

Note: I got the same issue with sending mails correctly on localhost, but on deployment it did not. Looks like the problem in my case was that I did not use port and host in createTransport, instead I had:

const mailTransport = nodemailer.createTransport({
  service: 'gmail',
  auth: {
    user: MAIL_ACCOUNT,
    pass: MAIL_PASSWORD
  }
});

On top of this do not forget about enabling Less secure app access to ON. Also https://accounts.google.com/DisplayUnlockCaptcha might be helpful.

Answer 2

When you execute an asynchronous operation in a background triggered Cloud Function, you must return a promise, in such a way the Cloud Function waits that this promise resolves in order to terminate.

This is very well explained in the official Firebase video series here: https://firebase.google.com/docs/functions/video-series/. In particular watch the three videos titled "Learn JavaScript Promises" (Parts 2 & 3 especially focus on background triggered Cloud Functions, but it really worth watching Part 1 before).

So you should modify your code as follows:

exports.sendEmails = functions.database.ref('/users/{userID}/credentials').onCreate((snap, context) => {

  const userID = context.params.userID;
  const vals = snap.val()

  userName = vals.name;
  emailRecepient = vals.email;

  return smtpTransport.sendMail(mailOptions);
});

If you want to print to the console the result of the email sending, you can do as follows:

  return smtpTransport.sendMail(mailOptions)
    .then((info) => console.log('Email sent: ' + info.response))
    .catch((error) => console.log("Error sending email ---- ", error));
});

---

Actually there is an official Cloud Functions sample that does exactly that, see https://github.com/firebase/functions-samples/blob/master/email-confirmation/functions/index.js