Advanced Email Tracking: How to Track Opens & Clicks with GTM Server-Side (Privacy-First Approach)

Email marketing remains one of the most effective channels for businesses to engage with their audience. However, tracking email engagement—such as opens and clicks—can be challenging due to increasing privacy measures (e.g., Apple's Mail Privacy Protection). By leveraging Google Tag Manager (GTM) Server-Side, you can implement a robust and privacy-compliant email tracking system.

Why Use GTM Server-Side for Email Tracking?

Traditional email tracking relies on client-side pixels embedded in emails. However, modern privacy protections limit their effectiveness. GTM Server-Side (sGTM) offers several benefits:

? Increased Data Accuracy: Bypasses ad blockers and privacy restrictions affecting client-side tracking.

? Privacy Compliance: Allows better control over data collection, aligning with GDPR and CCPA guidelines.

? Faster Performance: Reduces reliance on third-party scripts, improving email deliverability.

? Custom Data Processing: You can enrich and send data to multiple platforms (Google Analytics 4, BigQuery, etc.).

Step 1: Setting Up GTM Server-Side

Before tracking email opens and clicks, you must have GTM Server-Side configured. Follow these steps if you haven’t set it up yet:

Deploy GTM Server-Side Container:

• Set up a Google Cloud or self-hosted GTM server container.
• Link it to your existing client-side GTM container.

• Configure Your GTM sGTM Tagging Server:
• In GTM Server-Side, create a new tagging server and configure its domain (e.g., tracking.yourdomain.com).
• Enable Debugging:
• Use the Preview Mode in GTM to verify events and requests are processed correctly.

Step 2: Tracking Email Opens via GTM Server-Side

To track email opens, you need to embed a 1x1 tracking pixel in your email that routes data through your GTM Server-Side container.

1. Generate a Unique Tracking Pixel URL

Each email recipient should receive a unique tracking URL with user identifiers (e.g., hashed email, user ID). Example URL:

https://tracking.yourdomain.com/email-open?user_id=12345        

2. Embed the Pixel in Your Email

Add an image tag in your email’s HTML:

<img src="https://tracking.yourdomain.com/email-open?user_id={{USER_ID}}" width="1" height="1" style="display:none;" />        

3. Create a GTM Server-Side Client to Capture Opens

Inside GTM Server-Side:

• Go to Clients > New Client.
• Set up a custom client to listen for requests on /email-open.
• Extract query parameters like user_id.

4. Forward Data to Google Analytics 4 or BigQuery

In GTM sGTM, create a Tag to send the event to GA4:

• Tag Type: Google Analytics: GA4 Event
• Event Name: email_open
• Event Parameters: user_id → {{Query Parameter user_id}} timestamp → {{Timestamp}}

Now, every time a recipient opens an email, the tracking pixel sends a request to GTM sGTM, which logs the event.

Step 3: Tracking Email Clicks via GTM Server-Side

Tracking email clicks involves intercepting links and routing them through GTM Server-Side before redirecting the user.

1. Modify Email Links to Route via GTM

Instead of direct links, modify your email URLs to pass through your tracking domain.

Example:

<a >Click here</a>        

2. Create a GTM Server-Side Client for Clicks

• Add a new client in GTM sGTM to listen for /email-click requests.
• Capture parameters like user_id and url.

3. Set Up a Tag to Send Click Data to GA4

Create a GTM sGTM Tag to send click events to GA4:

• Tag Type: Google Analytics: GA4 Event
• Event Name: email_click
• Event Parameters:
• user_id → {{Query Parameter user_id}}
• destination_url → {{Query Parameter url}}

4. Redirect the User to the Destination URL

To ensure a seamless user experience, set up a Redirect Response:

• In your GTM sGTM Client, after logging the event, redirect users:

return new Response("", {
  status: 302,
  headers: {
    "Location": request.query.get("url"),
  },
});        

Now, when a recipient clicks a link in your email, GTM Server-Side tracks the event before redirecting them to the intended destination.

Step 4: Verifying & Debugging Tracking Implementation

To ensure your tracking works as expected:

Use GTM Preview Mode

• Enable preview mode in GTM Server-Side and send test emails.
• Verify that email open and click requests appear in the event logs.

Check Google Analytics 4 Events

• Open GA4 DebugView (Admin > DebugView).
• Look for email_open and email_click events with corresponding parameters.

Inspect Server Logs

If you’re using a custom GTM server, check logs to confirm incoming requests.

Conclusion

By implementing email open and click tracking via GTM Server-Side, you gain a privacy-compliant and ad-blocker-resistant method to measure email engagement. This approach ensures:

? More reliable tracking than client-side methods.

? Better compliance with privacy regulations like GDPR & CCPA.

? Flexibility to send data to GA4, BigQuery, or other destinations.

With privacy becoming a growing concern, server-side tracking is the future of email analytics. Implement this method today to gain deeper insights into your email performance while maintaining user trust. ??

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?? Pro Tip: Want even deeper tracking? Combine GTM sGTM with UTM parameters and first-party data enrichment for more granular analytics.

Would you like a hands-on guide for setting up a GTM Server? Let me know in the comments! ???

I’m passionate about empowering organizations with data-driven decision-making while respecting user privacy.

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