(Node.js) OAuth2 for a GMail using a P12 Service Account Key

See more GMail REST API Examples

Note: This example does not work for Personal Google Accounts where the email domain is @gmail.com

For more information, see https://www.chilkatsoft.com/google_workspace_setup_smtp_gmail.asp

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOS

var os = require('os');
if (os.platform() == 'win32') {  
  var chilkat = require('@chilkat/ck-node23-win64'); 
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node23-linux-arm');
    } else if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node23-linux-arm64');
    } else {
        var chilkat = require('@chilkat/ck-node23-linux-x64');
    }
} else if (os.platform() == 'darwin') {
  var chilkat = require('@chilkat/ck-node23-mac-universal');
}

function chilkatExample() {

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    var http = new chilkat.Http();

    // --------------------------------------------------------------------------------
    // For a step-by-step guide for setting up your Google Workspace service account,
    // see Setup Google Workspace Account for Sending SMTP GMail from a Service Account
    // --------------------------------------------------------------------------------
    // Begin by loading your Google service account key (.p12)
    var cert = new chilkat.Cert();
    var success = cert.LoadPfxFile("c:/someDirectory/keys/chilkat25-cbd7b42afbd8.p12","notasecret");
    if (success !== true) {
        console.log(cert.LastErrorText);
        return;
    }

    // The ISS is your service account email address ending in gserviceaccount.com.
    var iss = "chilkatsvc@chilkat25.iam.gserviceaccount.com";

    // The scope is always the following string:
    var scope = "https://mail.google.com/";

    // The sub is your company email address
    var oauth_sub = "bob@yourcompany.com";

    // The access token is valid for this number of seconds.
    var numSec = 3600;

    var accessToken = http.G_SvcOauthAccessToken(iss,scope,oauth_sub,numSec,cert);
    if (http.LastMethodSuccess !== true) {
        console.log(http.LastErrorText);
        return;
    }
    else {
        console.log("access token: " + accessToken);
    }

    // The access token allows us to send unlimited emails while it's valid. Once it expires, we must obtain and use a new one.

    // -----------------------------------------------------------------------
    var mailman = new chilkat.MailMan();

    // Set the properties for the GMail SMTP server:
    mailman.SmtpHost = "smtp.gmail.com";
    mailman.SmtpPort = 587;
    mailman.StartTLS = true;

    mailman.SmtpUsername = "bob@yourcompany.com";
    mailman.OAuth2AccessToken = accessToken;

    // Create a new email object
    var email = new chilkat.Email();

    email.Subject = "This is a test";
    email.Body = "This is a test";
    email.From = "Bob <bob@yourcompany.com>";
    success = email.AddTo("Recipient","recipient@example.com");
    // To add more recipients, call AddTo, AddCC, or AddBcc once per recipient.

    success = mailman.SendEmail(email);
    if (success !== true) {
        console.log(mailman.LastErrorText);
        return;
    }

    success = mailman.CloseSmtpConnection();
    if (success !== true) {
        console.log("Connection to SMTP server not closed cleanly.");
    }

    console.log("Successfully sent email using Gmail with a service account key.");

}

chilkatExample();