How to customize and use Litmus tracking codes for advanced email engagement insights

If you send marketing emails and you actually care about what happens after you hit “send,” you’ve probably heard about Litmus. Litmus is one of the go-to tools for email testing and analytics, but most folks only scratch the surface when it comes to tracking. If you’re tired of vague “opens” and want to dig into real engagement—who clicked, how long they read, what devices they used—this guide is for you. I’ll show you how to use Litmus tracking codes, customize them for your needs, and avoid common traps that waste your time.

Why Bother With Litmus Tracking Codes?

Let’s be honest: basic email stats are pretty useless these days. Open rates are unreliable (thanks, Apple Mail Privacy Protection). Clicks only tell part of the story. If you want real insights, you need to go deeper. That’s where Litmus tracking codes come in—they let you see:

  • Read time: Did anyone actually read your email, or just glance and delete?
  • Device and client data: Are people opening on iPhones, Outlook, or something weird?
  • Geography: Where in the world are your readers?
  • Forwarding and printing: Is your content getting shared?

But you have to set these tracking codes up right, and that’s where most marketers get tripped up.

Step 1: Understand What You Can (and Can’t) Track

Before adding any tracking pixel, know its limits. Litmus tracking codes are image-based, so they work a lot like old-school tracking pixels. This means:

What you CAN reliably track:

  • If the email was opened (sort of)
  • How long the email was in view (read time, with caveats)
  • What device and client opened it
  • Some location data (city/region, not exact address)

What you CANNOT reliably track:

  • Opens in privacy-protected environments (e.g., Apple Mail will mark everything as “opened,” even if nobody looked)
  • Whether someone actually read the content—only that the pixel loaded and stayed visible
  • Clicks on links, unless you use separate click tracking (Litmus tracking codes themselves don’t track clicks)

Pro tip: Don’t obsess over open rates. Focus on relative changes over time and combine Litmus data with your ESP's click tracking for a fuller picture.

Step 2: Generate Your Litmus Tracking Code

Assuming you already have a Litmus account, here’s how to get your tracking code:

  1. Log into Litmus.
  2. Head to the “Analytics” or “Tracking” section (Litmus changes its UI sometimes, but look for “Email Analytics”).
  3. Click “Create New Tracking Code” or a similar button.
  4. Fill in details:
  5. Email name: Use something specific. “April 2024 Newsletter” beats “Newsletter.”
  6. Campaign: Group related emails for better reporting.
  7. Optional settings: Some versions let you set privacy options or tracking preferences.

Litmus will spit out a small bit of HTML—usually a 1x1 pixel image tag. It looks something like this:

html

Important: Don’t resize, crop, or edit this image tag. Just copy it as-is.

Step 3: Place the Tracking Code in Your Email

Where you stick the code matters. Here’s what I recommend:

  • Paste right before </body> if your ESP allows raw HTML. This ensures the pixel loads after your main content.
  • If using a drag-and-drop editor, add a custom HTML block at the very end of your email.
  • Don’t place the pixel at the top. Some email clients only load images “below the fold” if the user scrolls.

Watch out: Some ESPs (like Mailchimp or HubSpot) strip out certain tags. Always send a test email to yourself and inspect the HTML to confirm the pixel is there.

Step 4: Customize Your Tracking Code for Advanced Insights

This is where people usually stop, but you can get smarter. Litmus tracking codes support URL parameters for extra data—think personalization or deeper campaign segmentation.

Common Customizations

  • Subscriber ID: Attach a unique ID to the tracking pixel so you can match engagement to a real person.
    Example: html

Most ESPs let you insert a merge tag (like {{ subscriber.id }}) here.

  • Campaign or Segment: Add params like &segment=premium or &source=welcome_series.

  • A/B Testing: Add &variant=A or &variant=B to track which version gets more engagement.

How to add these:
Edit the src URL in your pixel with the parameters you want. Separate them with & if you add more than one.

Caution:
- Don’t put personally identifiable info (like emails or names) in the URL—just use anonymous IDs. - Some ESPs mangle merge tags in image URLs, so test with live data.

Step 5: Send Test Emails and Validate Tracking

Never trust that it “just works.” Here’s what to do every time:

  • Send a test to yourself and a few colleagues using different devices and clients.
  • Check Litmus analytics for activity. If nothing shows up after a few test opens, something’s wrong.
  • Inspect the email’s HTML in your inbox:
  • View source and check if the tracking pixel is present and unbroken.
  • Make sure any merge tags (like {{ subscriber.id }}) are being replaced by real values.

Common issues:

  • ESP strips the pixel out
  • ESP rewrites URLs, breaking the tracking
  • Pixel gets blocked by aggressive image blockers

If you hit a wall, try sending from a different ESP, or use Litmus’s built-in email address to test.

Step 6: Read the Data (and Don’t Get Fooled)

Now for the fun part—but don’t get starry-eyed. Here’s how to make sense of what you see in Litmus analytics:

  • Opens: Ignore the raw number. Focus on trends and which segments/devices are driving real engagement.
  • Read time: Look for patterns—do most people skim, or do a subset actually read? If everyone has a 0s read time, your pixel might not be loading.
  • Device/client breakdown: This is gold. If 80% of opens are on mobile, optimize your design accordingly.
  • Geography: Useful for regional campaigns, but don’t overthink it—location data is fuzzy.
  • Forwarding and printing: Nice to know, but don’t build your strategy around it.

What to ignore: - “Unique opens” in Apple Mail will be inflated. Treat with caution. - Tiny sample sizes. Don’t draw conclusions from a handful of opens. - Vanity metrics. If it doesn’t drive an action, it’s just noise.

Step 7: Combine Litmus with Other Data Sources

Litmus tracking codes are just one piece of the puzzle. For a complete view:

  • Use your ESP’s click tracking. Litmus won’t tell you who clicked what.
  • If you use UTM parameters in links, check Google Analytics for downstream activity.
  • Some CRMs let you map Litmus data to contacts, but be careful about privacy and data hygiene.

Don’t:
- Try to Frankenstein together “single-customer views” unless you have a good reason (and legal clearance). - Overcomplicate things. Start simple, then add complexity only if you need it.

Pro Tips and Real-World Warnings

  • Some clients block all images by default. These people won’t show up in your data. Don’t assume they didn’t open.
  • Litmus isn’t magic. Engagement data is always an estimate, not gospel truth.
  • Don’t obsess over perfection. Use tracking to spot major trends, not nitpick every open.
  • Privacy is getting tighter. Be transparent with your subscribers and don’t push the limits.

Keep It Simple, Iterate Often

Litmus tracking codes can unlock tons of insights, but only if you set them up right—and know what not to trust. Start with basic tracking, customize as you go, and focus on what actually moves the needle for your business. Most importantly: keep it simple, watch for trends, and tweak your approach over time. That’s how you get real value out of email analytics—without drowning in the data.