Researchers from KU Leuven and Radboud University have revealed that email addresses of users are used to track, market, and analyze domains. This is done without consent.
The study involved crawling 2. 8 million pages from the top 100 websites, and found that as many as 1,844 websites allowed trackers to capture email addresses before form submission in the European Union, a number that jumped to 2,950 when the same set of websites were visited from the U.S.
“Emails (or their hashes) were sent to 174 distinct domains (eTLD+1) in the U.S. crawl, and 157 distinct domains in the EU crawl,” the researchers said. Furthermore, 52 websites were determined to be collecting passwords in the same manner, an issue that has since been addressed following responsible disclosure.
LiveRamp. Taboola. Adobe. Verizon. Yandex. Meta Platforms. TikTok. Salesforce. Listrak. Oracle. Yandex. Mixpanel. LogRocket. Lead in password-grabbing.
“Certain third parties send email addresses character-by-character, as the user types in their address,” the researchers said. “This behavior appears to be due to session replay scripts that collect users’ interactions with the page including key presses and mouse movements. “
fashion/beauty, online shopping, and general news emerging as the top categories ->
fashion/beauty, online shopping, general news, software/hardware, and business emerging as the top categories
Email address offers many benefits. Not only are they unique, enabling third-parties to track users across devices, it can also be employed to match their online and offline activities, say, in scenarios where they make an in-store purchase that requires them to share their email address or sign up for a loyalty card.
The idea of harvesting emails addresses from online forms even when they are not submitted, was also fuelled by the ongoing efforts by browser vendors. This has forced marketers to search for other static identifiers in order to track users.

This is not the first time such a concern has been raised. In June 2017, Gizmodo discovered that a third party called NaviStone was collecting personal information from mortgage calculator forms prior to their submission, with very few websites explicitly disclosing this practice in their privacy policy.
Fast forward five years later, not much has changed, the researchers said, what with websites related to fashion/beauty, online shopping, and general news emerging as the top categories with the most “leaky forms. “
“Despite filling email fields on hundreds of websites categorized as pornography, we have not a single email leak,” the findings show, noting how it lines up with previous studies that have shown that adult websites have relatively fewer third-party trackers when compared to general sites with comparable popularity.
What’s more, such a practice may be in violation of at least three different General Data Protection Regulation (GDPR) requirements in the E.U., contravening principles of transparency, purpose limitation, and user consent.
In recent years, browser makers with the notable exception of Google Chrome have introduced new mechanisms to curtail cross-site cookies, but both Apple Safari and Mozilla Firefox have been found to do nothing to protect against scripts that export email addresses for tracking purposes.
One way to stop this type of tracking is to use browser extensions like uBlock Origin, or to switch to browsers with built-in ad blocking capabilities.
“All users should be aware that trackers may collect personal data they input into web forms, even if it is not submitted.” The researchers recommended further investigations by browser developers and privacy tool designers, as well as data protection agencies.