Resend

Introduction

The Resend integration sends a transactional email through Resend when a Dodo Payments event occurs. Use it to confirm payments, welcome new subscribers, and tell customers when a payment fails, from your own sending domain.

This integration requires a Resend API key with Sending access and a sending domain verified in Resend. You also need access to Developer → Webhooks in the Dodo Payments dashboard.

Getting Started

Open the Webhook Section

In the Dodo Payments dashboard, go to Developer → Webhooks and click Add endpoint.

Add endpoint dialog with Resend selected in the Integration dropdown and the How to connect Resend steps

Select Resend

In Integration, select Resend. The dashboard fills in the Endpoint URL and the transformation code for Resend, and the How to connect Resend panel shows the setup steps.

Enter API Key

In Resend, open API Keys, click Create API Key, and give the key Sending access. Resend shows the key, which starts with re_, only once. Paste it into API key. Dodo Payments sends it as a bearer token in the Authorization header of every request to Resend.

Select Events

In Subscribed events, select only the events your transformation handles. An event that the transformation leaves unchanged reaches Resend in the Dodo Payments format, and Resend rejects it.

Configure Transformation

Under Transformation code, edit the handler so each subscribed event becomes a Resend email. Start from the examples.

Test & Create

Under Test this code, select an event type and click Simulate to preview the request to Resend. Then click Create endpoint.

Done

Dodo Payments now sends an email through Resend for each subscribed event. To see each delivery and Resend’s response, open the Logs tab in Developer → Webhooks.

Transformation Code Examples

Each handler sets webhook.url to Resend’s send-email endpoint and replaces webhook.payload with the email. Dodo Payments amounts are in the smallest currency unit, so the examples divide by 100 and show the currency code. For zero-decimal currencies such as JPY and KRW, use the amount as is.

Payment Confirmation Email

Send a receipt when a payment succeeds (payment.succeeded):

payment_confirmation.js

function handler(webhook) {
  if (webhook.eventType === "payment.succeeded") {
    const p = webhook.payload.data;
    webhook.url = "https://api.resend.com/emails";
    webhook.payload = {
      from: "payments@yourdomain.com",
      to: [p.customer.email],
      subject: "Payment Confirmation - " + (p.total_amount / 100).toFixed(2) + " " + p.currency,
      html: `
        <h2>Payment Successful!</h2>
        <p>Hi ${p.customer.name},</p>
        <p>Your payment of ${(p.total_amount / 100).toFixed(2)} ${p.currency} has been processed successfully.</p>
        <ul>
          <li><strong>Payment ID:</strong> ${p.payment_id}</li>
          <li><strong>Amount:</strong> ${(p.total_amount / 100).toFixed(2)} ${p.currency}</li>
          <li><strong>Date:</strong> ${new Date(webhook.payload.timestamp).toLocaleDateString()}</li>
          <li><strong>Method:</strong> ${p.payment_method || "Unknown"}</li>
        </ul>
        <p>Thank you for your business!</p>
      `,
      text: `Payment Successful! Your payment of ${(p.total_amount / 100).toFixed(2)} ${p.currency} has been processed. Payment ID: ${p.payment_id}`
    };
  }
  return webhook;
}

Subscription Welcome Email

Welcome a customer when a subscription becomes active (subscription.active):

subscription_welcome.js

function handler(webhook) {
  if (webhook.eventType === "subscription.active") {
    const s = webhook.payload.data;
    webhook.url = "https://api.resend.com/emails";
    webhook.payload = {
      from: "welcome@yourdomain.com",
      to: [s.customer.email],
      subject: "Welcome to Your Subscription!",
      html: `
        <h2>Welcome to Your Subscription!</h2>
        <p>Hi ${s.customer.name},</p>
        <p>Your subscription has been activated successfully.</p>
        <ul>
          <li><strong>Subscription ID:</strong> ${s.subscription_id}</li>
          <li><strong>Product:</strong> ${s.product_id}</li>
          <li><strong>Amount:</strong> ${(s.recurring_pre_tax_amount / 100).toFixed(2)} ${s.currency}/${s.payment_frequency_interval}</li>
          <li><strong>Next Billing:</strong> ${new Date(s.next_billing_date).toLocaleDateString()}</li>
        </ul>
        <p>You can manage your subscription anytime from your account dashboard.</p>
      `,
      text: `Welcome! Your subscription is now active. Amount: ${(s.recurring_pre_tax_amount / 100).toFixed(2)} ${s.currency}/${s.payment_frequency_interval}`
    };
  }
  return webhook;
}

Payment Failure Notification

Ask the customer to update their payment method when a payment fails (payment.failed):

payment_failure.js

function handler(webhook) {
  if (webhook.eventType === "payment.failed") {
    const p = webhook.payload.data;
    webhook.url = "https://api.resend.com/emails";
    webhook.payload = {
      from: "support@yourdomain.com",
      to: [p.customer.email],
      subject: "Payment Failed - Action Required",
      html: `
        <h2>Payment Failed</h2>
        <p>Hi ${p.customer.name},</p>
        <p>We were unable to process your payment of ${(p.total_amount / 100).toFixed(2)} ${p.currency}.</p>
        <ul>
          <li><strong>Payment ID:</strong> ${p.payment_id}</li>
          <li><strong>Amount:</strong> ${(p.total_amount / 100).toFixed(2)} ${p.currency}</li>
          <li><strong>Error:</strong> ${p.error_message || "Payment processing failed"}</li>
        </ul>
        <p>Please update your payment method or contact support for assistance.</p>
        <a href="https://yourdomain.com/update-payment">Update Payment Method</a>
      `,
      text: `Payment Failed: We couldn't process your ${(p.total_amount / 100).toFixed(2)} ${p.currency} payment. Please update your payment method.`
    };
  }
  return webhook;
}

Tips

Send from a domain you’ve verified in Resend, which improves deliverability.
Include both an html and a text version of each email.
Personalize content with customer data from the payload, such as customer.name.
Write subject lines that state the result or the action needed.
Include an unsubscribe link in any email that contains marketing content.
Preview each template with Simulate before you create the endpoint.
To skip an event in code, set webhook.cancel = true before you return the webhook. The logs record a skipped delivery as successful.

Troubleshooting

Emails Not Being Sent

Check that the API key is correct, active, and has Sending access. To replace it, edit the endpoint and paste a new key in API key.
Check that the sender domain is verified in Resend.
Check that the recipient email addresses are valid.
Check Resend’s sending limits and quotas for your plan.
Open the Logs tab in Developer → Webhooks and read Resend’s response to the failed delivery.

Transformation Errors

Check that the payload matches Resend’s send-email format. Resend requires from, to, and subject.
Check that every event your code handles sets all the required fields.
Check that the html value is well-formed HTML.
Check that the from address uses a domain verified in Resend.

External Integrations

Messaging

Workflow Automation

CRM

Email

Analytics

Pricing

Introduction

Getting Started

Transformation Code Examples

Payment Confirmation Email

Subscription Welcome Email

Payment Failure Notification

Tips

Troubleshooting

​Introduction

​Getting Started

​Transformation Code Examples

​Payment Confirmation Email

​Subscription Welcome Email

​Payment Failure Notification

​Tips

​Troubleshooting

Introduction

Getting Started

Transformation Code Examples

Payment Confirmation Email

Subscription Welcome Email

Payment Failure Notification

Tips

Troubleshooting