Sending multiple emails at once with nodemailer

 https://stackoverflow.com/questions/64412815/sending-multiple-emails-at-once-with-nodemailer

 static async resendUndeliveredMails() {
try {
  const mails = await findAll();
  const mailerPromises = mails.map((mail) => transporter.sendMail(mail.dataValues));
  const responses = await Promise.all(mailerPromises);
  console.log(responses, "All Mails Have Been Sent Successfully");
} catch (e) {
  console.log(e);
}

const nodemailer = require("nodemailer");

const transporter = nodemailer.createTransport({
  service: "gmail",
  auth: {
    user: "user",
    pass: "pass", // naturally, replace both with your real credentials or an application-specific password
  },
});

const mailOptions = {
  from: "user@gmail.com",
  to: "test@gmail.com",
  subject: "testing due",
  text: "Dudes, we really need your money.",
};

const mailOptions2 = {
  from: "user@gmail.com",
  to: "test1@gmail.com",
  subject: "LOL due",
  text: "Dudes, we really need your money.",
};

Promise.all([
  transporter.sendMail(mailOptions),
  transporter.sendMail(mailOptions2),
])
  .then((res) => console.log(res))
  .catch((err) => console.log(err));

Sending an email using NodeMailer & Gmail

Source: https://codeburst.io/sending-an-email-using-nodemailer-gmail-7cfa0712a799

inside your node.js file write

var transporter = nodemailer.createTransport({
 service: 'gmail',
 auth: {
        user: 'youremail@address.com',
        pass: 'yourpassword'
    }
});

We used gmail as our transport service.