How do I send an email when a user changes their address?

You can do this by detecting the address change in your backend and then triggering an email notification.

Common approach

1. Compare old vs. new address

When the user submits an update, check whether the address fields changed:

• street
• city
• state/province
• postal code
• country

If any of those changed, trigger an email.

2. Save the updated address

Update the user record in your database first, or in the same transaction if possible.

3. Send the email

Use an email service like:

• SendGrid
• Amazon SES
• Mailgun
• Postmark
• Nodemailer with SMTP

Example logic

Pseudocode

if (oldAddress !== newAddress) {
  saveNewAddress();
  sendEmail(user.email, "Your address was updated", "We noticed your address changed.");
}

Example in Node.js

const nodemailer = require("nodemailer");

async function updateAddress(userId, newAddress) {
  const user = await db.users.findById(userId);
  const oldAddress = user.address;

  const addressChanged =
    oldAddress.street !== newAddress.street ||
    oldAddress.city !== newAddress.city ||
    oldAddress.state !== newAddress.state ||
    oldAddress.zip !== newAddress.zip ||
    oldAddress.country !== newAddress.country;

  if (addressChanged) {
    await db.users.update(userId, { address: newAddress });

    const transporter = nodemailer.createTransport({
      host: "smtp.example.com",
      port: 587,
      auth: {
        user: "smtp-user",
        pass: "smtp-pass",
      },
    });

    await transporter.sendMail({
      from: "no-reply@yourapp.com",
      to: user.email,
      subject: "Your address has been updated",
      text: "We noticed your address was changed in your account.",
    });
  }
}

Better practice

If you want this to happen reliably:

• use a database trigger or application event
• send the email asynchronously via a background job queue
• log the change for audit purposes
• avoid sending duplicate emails if the user updates the same address twice quickly

If you want, I can also show you:

• a version for Python/Django
• PHP/Laravel
• Ruby on Rails
• React + Node backend
• or a database trigger approach