How do I send a login alert email?

A common way to send a login alert email is:

1. Detect a successful login

   • In your auth flow, add a hook right after authentication succeeds.

2. Gather alert details

   • User email/name
   • Login time
   • IP address
   • Approximate location/device/browser
   • A link to “report this wasn’t me” or review sessions

3. Send an email from your backend

   • Use an email service like:
     • SendGrid
     • Mailgun
     • Amazon SES
     • Postmark
     • SMTP via Nodemailer

4. Format the email clearly

   • Subject: New login to your account
   • Body: mention time, device, IP, and what to do if unexpected

5. Avoid blocking login

   • Send the email asynchronously/background job so login stays fast.

---

Example email content

Subject: New login to your account

Body:

We noticed a new login to your account on Sep 23, 2026 at 10:42 AM UTC.
Device: Chrome on Windows
IP Address: 203.0.113.42

If this was you, you can ignore this email.
If not, please reset your password immediately.

---

Example in Node.js using Nodemailer

import nodemailer from "nodemailer";

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

async function sendLoginAlert(userEmail, details) {
  await transporter.sendMail({
    from: process.env.EMAIL_USER,
    to: userEmail,
    subject: "New login to your account",
    text: `We noticed a new login.\n\nTime: ${details.time}\nIP: ${details.ip}\nDevice: ${details.device}\n\nIf this wasn't you, please reset your password.`,
  });
}

Call sendLoginAlert(...) after a successful login.

---

Best practices

• Send alerts only for:
  • new devices
  • new locations
  • suspicious logins
• Include a secure “review sessions” link
• Don’t expose too much sensitive info
• Rate-limit alerts to avoid spam

If you want, I can show you how to do this in Python, Node.js, PHP, Django, or Firebase.