Guide
Why Email Tracking Doesn't Always Work (And What Actually Helps)
Open tracking works by loading a tiny invisible image when the email is opened. If the recipient's mail client blocks images, uses a privacy relay, or has a tracker blocker installed, that image never loads and the open is not recorded. This affects every email tracker on the market, not just Vero. Link clicks bypass most of these blocks and are always the stronger signal.
How open tracking works
When you send a tracked email, Vero embeds a 1x1 transparent image in the message. That image is hosted on Vero's servers. When the recipient opens the email and their mail client loads images, the image is fetched, and Vero logs the timestamp, IP address, device, and approximate location behind that request.
This is the same mechanism every email tracker uses: Mailtrack, Mixmax, Yesware, HubSpot, and every other tool on the market. It is not a Vero-specific approach. It is how email tracking has worked since the early 2000s.
What can prevent an open from being detected
Several things can stop the pixel from loading. The most common: the recipient's mail client is set to block remote images by default. Outlook (desktop), Apple Mail with Mail Privacy Protection enabled, and many corporate webmail clients do this. If images never load, the pixel never fires, and the open is not recorded.
Privacy tools and tracker blockers are a second cause. Browser extensions like uBlock Origin, Privacy Badger, and Ghostery block tracking pixels on web-based mail clients. Recipients using Gmail in a browser with a tracker blocker installed will often not register an open even if they read the email.
Corporate and government networks sometimes use security proxies that prefetch email content on behalf of the recipient. When that happens, Vero may log an open that occurred on the proxy server rather than on the recipient's device. Vero's classification engine filters most of these out, but not all.
Finally, some mail clients delay loading images until the user explicitly clicks a button. In those cases, the open is logged when they load images, which may be seconds, minutes, or hours after they first saw the email.
Apple Mail Privacy Protection
Apple introduced Mail Privacy Protection (MPP) in iOS 15 and macOS Monterey. When enabled, Apple's servers prefetch all remote content in an email, including tracking pixels, before the email is ever opened. This triggers an open event immediately on delivery, from an Apple IP address, regardless of whether the recipient ever reads the message.
Vero's classification engine detects these Apple prefetch events and marks them separately so they do not appear as verified human opens. If you see no open recorded on an email sent to an iPhone user, they most likely have MPP enabled and chose not to load images manually, or Vero filtered the Apple prefetch and waited for a real open that never came.
Why link clicks are more reliable
Link clicks work differently. When Vero rewrites a link in your email, the recipient's click goes through Vero's server before reaching the destination. This happens in their browser, not their mail client, which means image-blocking settings and tracker blockers in the mail client do not apply. A click is almost always recorded accurately.
This is why a recipient who shows no opens but has clicked a link is a strong signal: they read the email (enough to click something) but their setup prevented the pixel from firing. If you are sending emails with a link you want recipients to act on, the click data is the number to watch.
What to do when an open is missing
If you believe a recipient read your email but Vero shows no open, the most likely explanation is one of the scenarios above. It is not a bug. This is a known, industry-wide limitation of pixel-based tracking.
The practical workaround: always include at least one link in emails where you need engagement data. A link to a document, a calendar invite, or even a landing page gives you a click signal that bypasses the pixel problem entirely. When both opens and clicks are available, use clicks as the ground truth and opens as supporting context.
Frequently asked questions
Not necessarily. Zero opens can mean the email was not opened, or it can mean the recipient's setup prevented the pixel from loading. Check whether you included a link: if you see clicks but no opens, tracking is working and the pixel was blocked on their end.
Yes. Mailtrack, Mixmax, Yesware, HubSpot, and every other pixel-based tracker face the same limitations. Image blocking and privacy tools affect the entire category. Any tracker that claims 100% accuracy is overstating what the technology can do.
Vero's service is tracking infrastructure: we log every event the technology can detect and classify events accurately. We cannot guarantee that a recipient's mail client will load images, and we cannot override privacy tools or Apple MPP on the recipient's device. These are end-user choices outside any tracker's control. Tracking not firing due to recipient-side image blocking is not a product failure.
Vero classifies every open event. A verified human open is one where the IP, timing, and user-agent are consistent with a real person reading the email on a device, as opposed to a mail provider's image proxy, an Apple MPP prefetch, or a security scanner. The classification is best-effort; it is not a legal or forensic guarantee.
Vero filters Apple MPP prefetch events and does not count them as verified opens. If a recipient uses Apple Mail with MPP on and never manually loads images, you will typically see no open recorded, which is the more accurate result.
Always include at least one tracked link. Send plain-text-friendly HTML so images load correctly when the client allows them. Avoid sending to addresses at domains known for aggressive security proxies. Use link clicks as your primary signal and open counts as secondary context.