How do I trigger emails from webhook events in my app?

A common way to trigger emails from webhook events is:

1. Receive the webhook

   • Your app exposes an endpoint like POST /webhooks/...
   • A third-party service (Stripe, GitHub, Shopify, etc.) sends event data to it

2. Verify the webhook

   • Check the signature or shared secret so you know the event is legitimate
   • Reject requests that fail verification

3. Parse the event

   • Inspect the event type, e.g.:
     • payment.succeeded
     • user.signup
     • order.shipped

4. Map event → email action

   • Decide what email to send for each event
   • Example:
     • user.signup → welcome email
     • invoice.paid → receipt
     • password.reset → reset instructions

5. Send the email

   • Call an email provider/API like:
     • SendGrid
     • Mailgun
     • Amazon SES
     • Postmark
     • Resend
   • Or queue a background job that sends the email asynchronously

6. Respond quickly to the webhook

   • Return 200 OK as soon as possible
   • Do the email sending in a background worker if possible, so webhook retries don’t happen due to slow processing

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Typical architecture

Webhook provider → your webhook endpoint → job queue → email service → user inbox

This is usually better than sending the email directly inside the webhook handler because it:

• avoids timeouts
• handles retries more safely
• makes the system more reliable

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Example flow

If Stripe sends payment_intent.succeeded:

• Webhook arrives at /webhooks/stripe
• You verify Stripe’s signature
• You detect payment_intent.succeeded
• You create a “payment receipt email” job
• A worker sends the email through SendGrid/Postmark/etc.

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Pseudocode

app.post("/webhooks", async (req, res) => {
  const event = verifyWebhook(req);

  if (event.type === "user.signup") {
    await queueEmail({
      to: event.data.email,
      template: "welcome",
      variables: { name: event.data.name }
    });
  }

  res.sendStatus(200);
});

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Important best practices

• Verify signatures
• Make handlers idempotent so duplicate webhook deliveries don’t send duplicate emails
• Use background jobs instead of sending inline if the email provider is slow
• Log failures and retry safely
• Store event IDs to deduplicate events

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If you want, I can show you a complete example in Node.js, Python, or PHP using a real email provider.