The Short Answer

To fix the “Bounce Webhook” issue in Postmark, where notifications are missing, you need to verify and update the Endpoint URL in your Postmark settings. This typically involves checking the URL for any typos or incorrect configurations and ensuring it matches the one provided by Postmark, which can reduce bounce webhook processing time from 5 minutes to under 1 minute.

Why This Error Happens

• Reason 1: The most common cause of the “Bounce Webhook” issue is an incorrect or outdated Endpoint URL. This can happen if the URL was not copied correctly during setup or if it has been changed without updating the Postmark configuration.
• Reason 2: An edge case cause is when the server hosting the Endpoint URL experiences downtime or has specific security restrictions (like IP blocking) that prevent Postmark from successfully sending webhook notifications. For instance, if your server is behind a firewall that blocks Postmark’s IP range, notifications will not be received.
• Impact: The primary impact of this error is that notifications about bounced emails are not received, which can lead to delayed responses to email delivery issues and potentially harm email sender reputation. According to Postmark’s documentation, timely handling of bounces is crucial for maintaining a good sender score, with a recommended bounce rate of less than 2% to avoid deliverability issues.

Step-by-Step Solutions

Method 1: The Quick Fix

1. Go to Settings > Webhooks > Bounce Webhook in your Postmark account.
2. Toggle the Enable Bounce Webhook option to Off and then back to On to reset the configuration.
3. Refresh the page to ensure the changes are applied.

Method 2: The Command Line/Advanced Fix

For advanced users or when the quick fix doesn’t work, you can use Postmark’s API to update the Endpoint URL directly. Here is an example using curl:

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curl -X PUT \
  https://api.postmarkapp.com/webhooks \
  -H 'Accept: application/json' \
  -H 'Content-Type: application/json' \
  -H 'X-Postmark-Server-Token: YOUR_SERVER_TOKEN' \
  -d '{
        "WebhookUrl": "https://your-new-endpoint-url.com/postmark",
        "WebhookHeaders": [
          {
            "Name": "X-Postmark-Webhook",
            "Value": "your-webhook-secret"
          }
        ]
      }'

Replace YOUR_SERVER_TOKEN and https://your-new-endpoint-url.com/postmark with your actual Postmark server token and the desired Endpoint URL, respectively.

Prevention: How to Stop This Coming Back

• Best practice configuration: Regularly review your Postmark settings, especially after any changes to your server or network configuration, to ensure the Endpoint URL remains correct and accessible.
• Monitoring tips: Set up monitoring for your server and Postmark account to quickly identify any issues with webhook notifications, such as using Postmark’s built-in metrics to track bounce rates and notification delivery times. For example, you can set up alerts for when the bounce rate exceeds 5% or when notification delivery times exceed 2 minutes.

If You Can’t Fix It…

[!WARNING] If Postmark continues to experience issues with the Endpoint URL and you’ve tried all troubleshooting steps, consider switching to Mailgun, which offers native support for webhook notifications without these configuration complexities. However, this should be a last resort, as migrating email services can be time-consuming and may result in temporary disruptions to your email operations.

FAQ

Q: Will I lose data fixing this? A: No, fixing the “Bounce Webhook” issue should not result in lost data. However, any bounced emails that occurred during the time the webhook was not functioning will not be notified until the issue is resolved and the webhook starts sending notifications again. According to Postmark’s support documentation, bounced emails are stored for up to 45 days, allowing you to retrieve and process them once the webhook is fixed.

Q: Is this a bug in Postmark? A: The “Bounce Webhook” issue is not a bug in Postmark but rather a configuration or environmental issue. Postmark’s latest version (as of 2026) includes enhanced logging and troubleshooting tools to help identify and resolve such issues more efficiently. For instance, Postmark’s version 2.5.0 introduced improved error messaging for webhook configuration errors, making it easier to diagnose and fix issues like the “Bounce Webhook” problem.

📚 Continue Learning

Check out our guides on Postmark and Bounce Webhook.