What is Tracking Pixel?
A tracking pixel is a tiny, invisible image embedded in emails that records when recipients open the message, providing open rate metrics to senders.
A tracking pixel (also called a web beacon or 1x1 pixel) is a minuscule, typically transparent image embedded in HTML emails. When a recipient opens the email and their client loads images, it fetches the pixel from the sender's server—recording the open event.
How it works: 1. Sender embeds a unique image URL in the email (often personalized per recipient) 2. Recipient opens email and their client requests the image 3. Server logs the request: timestamp, IP address, user agent 4. Sender now knows the email was opened
Tracking pixels are controversial. They provide valuable engagement data but raise privacy concerns. Many email clients now block external images by default, proxy images through their own servers, or prefetch images regardless of opens—making pixel tracking increasingly unreliable.
Why Tracking Pixel Matters
Tracking pixels have been the primary way to measure email engagement for decades. However, their reliability is declining. Apple's Mail Privacy Protection, Gmail's image proxying, and corporate email security solutions all interfere with pixel tracking. Understanding these limitations helps you interpret open rate data correctly and consider alternative engagement signals.
How Ark Handles Tracking Pixel
Ark includes open tracking via tracking pixels, but we're transparent about their limitations. We recommend using click tracking as a more reliable engagement signal for transactional emails. Our webhook events include both opens and clicks, clearly labeled, so you can build engagement tracking appropriate for your use case.
Frequently Asked Questions
Are tracking pixels accurate?
Increasingly no. Apple Mail Privacy Protection pre-fetches images, inflating open rates. Many corporate clients block images entirely, underreporting opens. Gmail proxies images, hiding geographic and device data. Use open rates as directional signals, not precise metrics.
Do tracking pixels work in plain text emails?
No. Tracking pixels require HTML emails since they're embedded as image tags. Plain text emails cannot contain tracking pixels, which is one reason privacy-conscious recipients prefer them.
Can recipients block tracking pixels?
Yes, in several ways: disable automatic image loading, use privacy-focused email clients, enable Apple Mail Privacy Protection, or use browser extensions. Many users aren't aware these options exist, but adoption is growing.
Are tracking pixels a privacy concern?
Yes, they can reveal when you read email, how many times, your IP address (approximate location), and device type. This is why privacy advocates recommend disabling automatic image loading and why providers are adding protective features.
Related Terms
Open Rate
Open rate is an email metric showing the percentage of delivered emails that recipients opened, typi...
Click-Through Rate
Click-through rate (CTR) is an email metric measuring the percentage of recipients who clicked a lin...
Email Deliverability
Email deliverability is the ability to successfully deliver emails to recipients' inboxes rather tha...
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