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Sending Emails Securely Using Node.js, Nodemailer, SMTP, Gmail, and OAuth2

Chandra Panta Chhetri on December 16, 2020

Many solutions online regarding configuring Nodemailer to use your Gmail requires you to enable less secure app access. If that sounds too scary fo...

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Palak Kotwani • Mar 30 '21

I am getting this error . UnhandledPromiseRejectionWarning: Failed to create access token :(
(Use node --trace-warnings ... to show where the warning was created)
(node:7900) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag --unhandled-rejections=strict (see nodejs.org/api/cli.html#cli_unhand...). (rejection id: 1)
(node:7900) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise

Nokha Debbarma • May 28 '21

As sendEMail is a async function try add try-catch block inside sendEmail function.

Luteya Coulston • Apr 5 '21

I'm getting the same, did you find a solution?

Nokha Debbarma • May 28 '21 • Edited

As sendEMail is a async function try adding try-catch block inside sendEmail function.

sailee14 • Mar 13 '22

After adding try catch block getting "Error: No refresh token or refresh handler callback is set." this error. Any way to make it right?

Tony Silvestri • Jun 29 '22 • Edited

Hi
I'm consistently getting this error:
"Failed to create access token: Error: invalid_grant" after having an app work fine for a week or so. After this period this error pops up.

I go to OAuth playground to regenerate the refreshToken. App works fine only to fail sometime later.

I pretty much followed (heck copied!! :-)) the code offered in this article.

Any ideas? Much appreciation in advance!

Abeer • Jul 5 '22 • Edited

Add the email you are using to send email here in OAuth consent screen page as a test user

Tony Silvestri • Jul 5 '22

Hi. It's there already. But Thx for replying!!!

Abeer • Jul 5 '22

I will write a blog on it. once writing is completed, I will leave a link here

Tony Silvestri • Jul 5 '22

Thank you for your efforts! They are much appreciated.
Tony

springboot20 • Oct 2 '23

please am having a problem with sending dynamic email using nodemailer express handlebars here is my code
import nodemailer from "nodemailer"
import {
google
} from "googleapis"
import fs from "fs"
import path from "path"
import url from "url"
import expressHandlerbars from "nodemailer-express-handlebars"

const filename = url.fileURLToPath(import.meta.url)
const __dirname = path.dirname(filename)

const OAuth2 = google.auth.OAuth2
const createTransporter = async () => {
const OAuth2Client = new OAuth2(
process.env.CLIENT_ID,
process.env.CLIENT_SECRET,
"developer.google.com/oauthplayground"
)

OAuth2Client.setCredentials({
refresh_token: process.env.REFRESH_TOKEN
})

const accessToken = await new Promise((resolve, reject)=> {
OAuth2Client.getAccessToken((error, token => {
if (error) {
console.log(error)
reject("Failed to get accessToken")
}
resolve(token)
}))
})

return await nodemailer.createTransport({
service: "gmail",
auth: {
type: "OAuth2",
accessToken,
user: process.env.EMAIL,
refreshToken: process.env.REFRESH_TOKEN,
clientId: process.env.CLIENT_ID,
clientSecret: process.env.CLIENT_SECRET,
}, tsl: {
rejectUnauthorized: false
}
})
}

const sendMail = async (email, subject, payload, template)=> {
const options = {
from: process.env.EMAIL,
to: email,
subject:subject,
template: template,
context: payload,
}

try {
const transporter = await createTransporter()

transporter.use("compile", expressHandlebars({
  viewEngine: {
    extName: '.hbs',
    partialsDir: 'views/partials',
    layoutsDir: 'views/layouts',
    defaultLayout: 'layout',
  },
  extName: '.hbs',
  viewPath: 'views',
}))

await transporter.sendMail(options)

} catch(error) {
console.log(${error})
}
}

export default sendMail
so I am receiving a reference error how can I fix it and do it in the right way

Pawel Oz • Feb 5 '22

I actually dont understand what happens next, in production. I guess oauthplayground does not stay there and we need to implement our authorization endpoint (redirect_uri) which is not much covered in the article. I think we should not use oauthplayground refresh token in production?

Jason • Feb 12 '23

Thank you so much, Chandra!

I was able to follow your directions for my Next.js application and got it to work!

This OAUTH stuff is definitely not intuitive, though.

For anyone struggling with implementing this, here is the GitHub link for my little project: github.com/jason-warner/hustlin-la...

And a few tips:

be extra careful to wrap your requests in try/catch
do not append your ENV variables with a semicolon ( ; )
use console logs to confirm every single one of your assumptions (you have access to environment variables, you have a an access token before you try to send mail, etc. and log any possible errors)

Pat Nuzum • Mar 25 '21

I am getting the following error:
Error: Invalid login: 535-5.7.8 Username and Password not accepted.

It works correct when I run your program in a standalone mode, but when I am your logic to my project, I get the above error.

Nandhakumar • Dec 31 '21

Were you able to fix the issue?

Joshua T Jackson • Jan 23 '21

What's the point of using Nodemailer when you can send emails using just the Gmail API?

Alohe • Mar 19 '21

Its easier to implement i guess

lefterispour • Feb 5 '23

When I'm clicking to authorize API's and selecting my google account I'm getting this error: "appname has not completed the Google verification process. The app is currently being tested, and can only be accessed by developer-approved testers. If you think you should have access, contact the developer.
If you are a developer of appname, see error details.
Error 403: access_denied.

SMoZam • Apr 14 '21

Hey,
Thanks for this post.
Refresh token expires in one week for me is it normal ?
Thanks

Yourispen TANKO MBA ESSONO • Jan 18

Hi. I hope you're doing well. I used your method and everything works correctly, but only locally. In production (on Vercel for example), emails never go out. I do not understand. Can you help me please?