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node.jsoauth-2.0nodemailer

What is the definitive way to use Gmail with OAuth and Nodemailer?

Desired Behaviour

Use Gmail, OAuth2 and Nodemailer to send an email from a server side node.js file.

What I've Tried

Relevant Documentation

https://nodemailer.com/smtp/oauth2
https://nodemailer.com/usage/using-gmail
https://developers.google.com/gmail/api/auth/web-server

Relevant Questions

send emails from MY gmail account with OAuth2 and nodemailer
How do I authorise an app (web or installed) without user intervention?
https://stackoverflow.com/a/47936349
https://stackoverflow.com/a/22572776

There were gaps in the instructions of the above sources and some information was outdated, so the answer below was my final implementation which appears to be working.

I'm posting this solution for confirmation it is best practice and, if it is, to save others time.

Solution

  • The following worked for me, there are two parts:

    01) app.js

    02) Google and OAuth2 setup

    app.js

    var nodemailer = require("nodemailer");

var transporter = nodemailer.createTransport({
    host: 'smtp.gmail.com',
    port: 465,
    secure: true,
    auth: {
        type: 'OAuth2',
        user: local_settings.my_gmail_username,
        clientId: local_settings.my_oauth_client_id,
        clientSecret: local_settings.my_oauth_client_secret,
        refreshToken: local_settings.my_oauth_refresh_token,
        accessToken: local_settings.my_oauth_access_token
    }
});


var mail = {
    from: "John Smith <me@mydomain.com>",
    to: "user@userdomain.com",
    subject: "Registration successful",
    text: "You successfully registered an account at www.mydomain.com",
    html: "<p>You successfully registered an account at www.mydomain.com</p>"
}

transporter.sendMail(mail, function(err, info) {
    if (err) {
        console.log(err);
    } else {
        // see https://nodemailer.com/usage
        console.log("info.messageId: " + info.messageId);
        console.log("info.envelope: " + info.envelope);
        console.log("info.accepted: " + info.accepted);
        console.log("info.rejected: " + info.rejected);
        console.log("info.pending: " + info.pending);
        console.log("info.response: " + info.response);
    }
    transporter.close();
});

    Google and OAuth Setup

    The code above requires the following setup:

    01) Go to https://console.developers.google.com

    02) If you don't have a project, you will be prompted to create one

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    03) Click on Create Project

    04) Click on Create

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    05) Enter a Project Name and click Create

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    06) Select the Gmail API

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    07) Click on Enable

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    08) Click on Create Credentials

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    09) Enter the required settings

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    10) Give the OAuth client a name and ensure you add https://developers.google.com/oauthplayground as a redirect URI in order to generate the refresh and access tokens later

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    11) Define the consent screen settings

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    12) Click I'll do this later and Done

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    13) Click on the Edit icon, to view your Client ID and Client Secret

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    14) To generate access and refresh tokens, go to https://developers.google.com/oauthplayground

    15) Click on the cog icon in the top right, check Use your own OAuth credentials and enter Client ID and Client Secret

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    16) In the left column, select Gmail API v1 and click Authorise APIs

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    17) If you are signed into multiple accounts, when prompted select the relevant account

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    18) Click Allow

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    19) Click Exchange authorisation code for tokens

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    I'm not sure why there is a count down on the access token, but hopefully the message at the bottom of the screen means that the token won't expire.