: Automating Emails to Notify Users Two Days Before Free Trial Ends

Hello,

I'm currently working on automating an email notification system where users who are on a free trial receive an email automatically 5 days after their initial sign-up. I'm using webhooks for this purpose. Below is the implementation snippet using Node.js, Express, and Nodemailer:

require("dotenv").config();
const express = require("express");
const bodyParser = require("body-parser");
const nodemailer = require("nodemailer");

const app = express();
const port = 3000;

app.use(bodyParser.json());

const transporter = nodemailer.createTransport({
  service: "gmail",
  auth: {
    user: process.env.EMAIL_USER,
    pass: process.env.EMAIL_PASS,
  },
});

async function sendMail({ to, from, subject, html }) {
  try {
    let info = await transporter.sendMail({
      from: from,
      to: to,
      subject: subject,
      html: html,
    });
    console.log("Message sent: %s", info.messageId);
    return "Email sent successfully";
  } catch (error) {
    console.error("Error sending email: %s", error);
    return "Failed to send email";
  }
}

app.post("/webhook", async (req, res) => {
  const authHeader = req.headers.authorization;
  const expectedAuthToken = process.env.AUTH_TOKEN;

  if (!authHeader || authHeader !== `Bearer ${expectedAuthToken}`) {
    return res.status(401).send("Unauthorized");
  }

  const data = req.body;

  if (
    data.event.type === "INITIAL_PURCHASE" &&
    data.event.data.period_type === "TRIAL"
  ) {
    const userId = data.event.data.app_user_id;
    const emailAddress = data.event.data.email;

    setTimeout(async () => {
      const message = await sendMail({
        from: process.env.EMAIL_USER,
        to: emailAddress,
        subject: "Reminder: Your Subscription Benefits",
        html: `<h1>Hello!</h1><p>Thank you for subscribing. Don't forget all the great features you can access!</p>`,
      });
      console.log(message);
    }, 432000000); // 5 days in milliseconds

    res.send("Webhook processed, email will be sent in 5 days.");
  } else {
    res.status(200).send("Webhook received, but no relevant action needed.");
  }
});

app.listen(port, () => {
  console.log(`Server running on port ${port}`);
});
 

Could you please review this setup and let me know if there are any potential issues with using webhooks in this manner or if there's a better approach to achieve the same functionality?

Thank you for your guidance!