Email Tracking Pixels: A Closer Look at Their Benefits and Challenges 

Email tracking pixel cover image with Invader art

Tracking pixels are the standard mechanism for measuring open rates. These tiny invisible images have long helped shine a light on recipient behavior. But they’re becoming less reliable due to the rise of privacy tools and email clients designed to block invasive content. 

If you manage email campaigns, you’ve definitely faced the dilemma of balancing effective analytics with user privacy.

So, let’s discuss the role of email tracking pixels — how they work, whether they’re legal, and how privacy protection mechanisms affect them. 

What Is the Purpose of an Email Tracking Pixel? 

An email tracking pixel is a tiny image, usually the size of just one pixel, embedded in the HTML code of emails. It’s often a transparent image, like a PNG, so it’s invisible to recipients.

Your email marketing platform creates and embeds the pixel for you in every email you send. And you can create your own if you want to embed it in an email. We’ll show you how later on.  

This pixel is a helpful tool for:  

  1. Measuring email open rates: The primary function of tracking pixels is to monitor whether your email has been opened. This metric gives you a direct insight into the initial engagement level of your campaign. 
  2. Understanding recipient behavior: Beyond just open rates, tracking pixels provide a window into how recipients interact with your email. Do they open it immediately or let it sit for days? Do they reopen it multiple times? This information can help you optimize send times for maximum engagement.
  3. Optimizing campaign effectiveness and personalization: The data from tracking pixels lets you measure the effectiveness of different email content. You can tailor future campaigns to better align with your audience’s interests and behaviors. 
  4. Enhancing audience segmentation: You can segment your audience based on their engagement levels and interactions using the data you obtain from tracking pixels. This segmentation strategy helps you send more targeted and relevant email campaigns. 

What Information Can You Collect Using Tracking Pixels? 

The most direct metric a tracking pixel can measure is the open rate, the percentage of emails opened to the total number of emails sent. Open rates are crucial for measuring the initial success of your subject line and the overall appeal of your email.

Tracking pixels can give you more information, though. Here are some of the details you can expect: 

Open frequencyHow many times each user opens each email.
Device typeThe type of device used to open the email (mobile, desktop, etc.).
Email clientThe email client (like Gmail, Outlook) or browser used to view the email.
LocationThe user’s email IP address can give you a rough idea of their geographic location.
The information you can obtain using a tracking pixel

You can use the tracking pixel to measure more complex metrics, but they require a more complex setup. Let’s consider two of them. 

Time Spent on Email

This metric is less straightforward than tracking opens because it requires continually pinging the tracking pixel. 

The system should record the time when the user first opens the email and when they close it, navigate to another tab, or return to the inbox. The difference between these times gives an estimate of how long the recipient actively viewed the email. 

It’s not possible to calculate this metric on all platforms, especially web-based email clients. 


In cases where the email’s goal is to drive sales or sign-ups, your analytics software can use data from the tracking pixel to check whether the recipient took the desired action after clicking a link in the email

To achieve this, you need to integrate the tracking pixel with web analytics tools to connect the user’s email ID with their session ID on your website. 

Note that this isn’t the only way to track conversions. For example, a common approach is to append UTM parameters to the links in your emails. Your analytics software will then capture these parameters and analyze user behavior accordingly. 

Tracking Pixels Do Not Collect Personal Information 

Tracking pixels gather data about interactions with the email, such as opens and clicks, but they don’t have access to or store personal details like names, addresses, or phone numbers. Plus, if a user is on an email list, their email address is already known. 

These pixels can still raise privacy concerns, though. That’s because some users might be uncomfortable knowing that someone knows about their email behavior. 

The key concern isn’t about personal data, but about the perception of being watched, which can feel intrusive to some users. So, you need to balance the use of tracking pixels with respect for user privacy and transparency.

Plus, as you collect more data from tracking pixels, you can paint a detailed picture of a user’s email behavior and preferences. And if someone combines this data with data from other sources, they can infer personal details or preferences. So, it’s understandable that some users try different methods to disable tracking pixels. 

Is Email Pixel Tracking Legal?  

Using email tracking pixels isn’t illegal unless a law strictly bans it. So, if your subscribers live in an area without specific protection laws, you can use tracking pixels without worrying about breaking the law. 

If your audience includes European residents, you have to abide by the GDPR, which specifically prohibits email tracking without express consent. What does that mean? 

It means you have to include a statement about using tracking pixels in your terms of service, and the user must agree to it before you record their email address in your database.  

The California Consumer Protection Act (CCPA), the equivalent of GDPR for California residents, has similar requirements — you have to inform your users that you’re tracking whether or not they open your emails. 

Benefits of Email Tracking Pixels for Audiences

There’s a misconception that a tracking pixel only serves the interests of marketers, with no real benefits for the recipients. But that’s not entirely true. 

Tracking pixels can actually enhance user experience and provide value to recipients. Let’s explore how: 

Personalized Content 

When you understand what type of content engages your audience, you can eliminate irrelevant content and send more focused emails that resonate with your audience

For example, if a tracking pixel shows that your subscribers are more likely to open emails about B2B email marketing, you can focus future emails more on this area. Maybe you can send in-depth guides on marketing techniques or case studies of successful campaigns.

Conversely, if you notice that your audience rarely opens emails about email security, you can avoid sending technical content to them. 

This way, your recipients get more of what they find valuable, which translates to more user engagement and satisfaction

Optimized Send Times 

The data from tracking pixels lets you pinpoint the most effective times to send emails. Maybe your users are more likely to open emails in the early evening or during lunch breaks. Or they prefer a weekly digest over daily updates. 

This way, your subscribers will receive emails at the most convenient and preferred times. So, they’re less likely to experience interruptions. 

More Accurate Segmentation 

The data from tracking pixels lets you identify patterns and preferences unique to each user. You can then cluster these preferences to create highly targeted segments based on actual user behavior rather than broad assumptions. 

This way, users get emails tailored to their specific preferences, such as topics they engage with the most or products they like.

Better User Experience 

Every time a user interacts with an email, the tracking pixel captures valuable feedback. You can use this feedback to identify the weak spots in your operations

This might lead to many improvements, such as: 

  • Evolving the design for better readability on mobile devices.
  • Adjusting the tone and language to better match user preferences.
  • Changing the type of content based on what’s resonating. 

In the long term, this commitment to adaptation and improvement means users will have a better experience with your emails

Automatic Unsubscribes 

When a tracking pixel indicates that a user consistently doesn’t engage with your emails, you can set up an automatic trigger to remove them from your list. 

This way, you respect that the user may have lost interest in your content from the time they opted in. Plus, they won’t have to tolerate an inbox cluttered with emails they don’t want. 

As a side benefit, you’ll have a cleaner list filled with individuals who are interested in your content. This translates into higher engagements and lower unsubscribe and spam complaint rates. 

How Does an Email Tracking Pixel Measure Engagement?

The basic function of an email tracking pixel is to capture the moment an email is opened. 

Let’s explore how that happens: 

  1. User opens email: The pixel itself doesn’t include any information. It’s a file hosted on a server. When you open the email containing the pixel, the email client (like Outlook, Gmail, etc.) treats that pixel like any other image. 
  2. Client fetches the pixel: The client makes a request to the server to download the pixel. The HTTP request header usually contains data like the time of the request and the type of device used to open the email. 
  3. Server logs the request: When the request reaches the server, it records the details. This is how the sender knows the recipient opened the email. Each time the user opens the email, a new request gets triggered. So, the sender can track not just if the email is opened, but how many times.

Tracking Pixels: A Technical Deep Dive 

Let’s consider the implementation aspect of tracking pixels. The basic setup for tracking emails uses an HTML <img> tag, while more modern options for web tracking use JavaScript. Let’s consider both. 

HTML Tracking Pixels

If you look at the HTML code of an email, a typical tracking pixel looks like this: 

<img src=”  height=”1” width=”1” style=”display:none”/>

In this example, the src attribute points to the URL where the tracking pixel is hosted. The height and width are set to 1 to make the image as small as possible. The style attribute with display:none ensures the pixel isn’t visible in the email.

Each tracking pixel URL is usually unique to each recipient. It’s easy to generate unique URLs using parameters. 

For example, the URL might look like

Any piece of information following the question mark in the URL is called a parameter. The parameter user_id=12345 is unique to a single recipient. So, the sender can track which users open which emails. 

Strategies Against Blockers

The tracking pixel’s code might appear slightly different from one email marketing service to another. The differences might be because of the company’s coding standards. But the more important reason is to to bypass image blockers and privacy tools that detect and disable tracking pixels

Here are a few common tactics:

  • Inline CSS: Using inline CSS styles (like display:none; or setting opacity to 0) to hide the tracking pixel while making sure it still loads.
  • Encrypting the URL parameters: Encrypting the URL of the pixel can make it harder for email clients to recognize because they can’t read the information in the URL. 
  • Non-parameterized image URLs: The pixel src looks like a standard URL without any obvious parameters, but it can include unique IDs or hints for server-side code to identify the user and detect whether they opened an email. 

To help you see what an actual tracking pixel looks like, here’s one from our campaigns:

email tracking pixel code
A real-life tracking pixel rendered in Gmail

If you look closely, the src attribute consists of two URLs separated by #. This is how Gmail treats images. It routes them through a proxy using (i.e., But the tracking pixel is actually hosted on Other email clients might treat the pixel differently. 

JavaScript Tracking 

JavaScript is a programming language that lets you create dynamic content for websites and emails. It’s also a great tool for collecting analytics data from user behavior

It has two advantages over static HTML: 

  1. It can record user behavior in the background. So, users can continue browsing or reading without any annoying page refreshes or interruptions. 
  2. It offers more flexibility and can collect a broader range of data, such as how long someone spends reading a page. 

There is a catch, though; many email clients disable JavaScript for security reasons. This is one of the biggest reasons the HTML pixels are still in use in email marketing and why JavaScript tracking is much more common on websites. 

How To Create a Tracking Pixel for Email Campaigns 

Setting up a tracking pixel from scratch isn’t easy; it needs some technical skills and access to a private email server. So, it’s more practical to use the built-in tools in your email marketing platform. 

Tracking open rates is a pretty basic functionality in email marketing, so you can expect any platform to offer this feature. 

Another option is to sign up with dedicated email analytics platforms like Litmus or Email on Acid, which offer advanced tracking and analytics features. 

If you’re looking for something simpler, you can install the OpendOrNot Chrome extension which lets you track emails on Gmail. 

How To Find a Tracking Pixel in Email

If you want to make sure your tracking pixel is working correctly or want to check a competitor’s tracking pixel, you have a few options: 

Pixel Blocker Extensions

There are browser extensions and Gmail addons that inspect incoming emails for tracking pixels. Their primary purpose is to notify users or block tracking pixels altogether. But you can also use them to make sure the tracking pixels in your campaigns are working correctly. 

The top option is Ugly Email, an open-source extension for Chrome and FireFox. 

It detects tracking pixels developed by 58 common email marketing platforms like SendGrid and Constant Contact. It displays an eye icon next to the subject line if it detects a tracking pixel. 

Other options include Trocker and PixelBlock

Sending a Test Email

A practical approach is to send test emails to yourself or a test account. Once you send the test email, log on to your test account and open the email to see if the open registers on your email marketing platform. It’s a good practice to test across different email clients and devices.

Manual Inspection

If you’re comfortable with HTML, digging into the code is a surefire way to locate your tracking pixel.

Follow these steps: 

  1. Send a test email, log on to the receiving account, and open the email. 
  2. Scroll to the bottom of the email content
  3. Right-click on a random element and click Inspect
  4. Look for a closing table tag — i.e., </table>. 
  5. The tracking pixel is usually a few lines below that tag. 

Why look for the pixel at the bottom? Because it’s standard practice to put it after the content to make sure the email content loads correctly even if the pixel fails. 

Here’s an example: 

A tracker pixel in HTML code

Challenges Posed by Pixel Blockers and Privacy Tools

So far we’ve established that tracking pixels aren’t as harmful as many paint them to be. Still, some users prefer to stay hidden. And that’s why there’s an entire category of tools and mechanisms dedicated to making tracking pixels ineffective. 

Apple’s Mail Privacy Protection

Apple’s MPP, part of iOS 15, disrupted how email tracking works. It automatically preloads and caches images, including tracking pixels, regardless of whether the user opens the email. 

So, if an Apple user has the setting turned on, all their emails register a fake open even if they never click on the subject line. 

The collective impact of the MPP is so drastic that the global open rate shot up from 19 percent to 31 percent the year after Apple rolled out the feature. In the meantime, other user behavior metrics stayed almost the same. 

Privacy-Focused Email Clients

Privacy-focused email clients, such as Proton Mail, give users with more control over their data. They often use email encryption to provide more security compared to Gmail. 

Another common feature in these clients is preventing senders from tracking email opens or other interactions

Some clients send a fake open for all received emails, while others block the tracking pixel and completely hide the user’s activity. The user can configure the client to block all images in emails or just the tracking pixel. 

Pixel Blockers

We touched on these earlier. Pixels blockers are browser or email client extensions designed to target tracking pixels. They can prevent tracking pixels from loading or communicating data back to the sender. But they won’t affect non-tracking images in the email. 

They usually work by matching the image code to known pixel patterns. So, they’re not always accurate, and they’re easy to beat. 

Alternative Techniques: Email Tracking Without Pixels

As users start to become more conscious about their privacy, you need to figure out smarter ways to measure your email marketing performance

Here are a few ideas: 

  • Benchmark non-Apple users: Non-Apple devices don’t have mechanisms like the MPP. And it’s safe to assume that user behavior is mostly consistent across devices. So, you can benchmark open rates on other devices and generalize the results to your entire audience. 
  • Link tracking: Embed unique links in your emails. When recipients click these links, you can track this interaction and gain insights into their interests. 
  • Email replies: Analyzing direct responses from recipients can be a powerful way to measure engagement. Replies indicate a high level of interest and provide qualitative data that pixel tracking can’t capture.
  • Other engagement metrics: Click rate and click-through rate measure how subscribers react to your content. These metrics are still relevant even if users disable tracking pixels because they don’t rely on open rates. 

See the True Picture with Campaign Refinery Metrics Approach

At Campaign Refinery, we help you achieve genuine, measurable success in your email campaigns. 

We don’t just measure numbers, we give you deep, authentic insights into each campaign’s true performance. That’s why we’ve meticulously defined every metric to mirror your actual impact, without inflating successes. 

And with our user-friendly interface, it’s a breeze to get the most out of every email you send. 

Apply to join Campaign Refinery for genuine insights and genuine success. 

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