Chapter 3: Introduction to Technological Aspects of Privacy
Tracking Email Recipients and Cross-Device Tracking
HTML email can track opens via a unique tracking pixel; reading in plain text defeats it. Cross-device tracking links a user across devices using deterministic tracking (login-based) or probabilistic tracking (inferred from IPs, cookies, location).
HTML email can track opens: a tracking pixel - a small image with a user-unique link - loads when the email is opened. To prevent it, the user can disable HTML and read in plain text.
| Technique | Basis |
|---|---|
| Deterministic tracking | Based on the same user login observed across multiple devices |
| Probabilistic tracking | Based on inferences from IP addresses, cookies, location, and behavioral data |
Key terms - quick answers
What is “Tracking pixel”?
A small image with a user-unique link or filename loaded when an email is opened, indicating the open (and clicks); disabled by reading in plain text.
What is “Cross-device tracking”?
The ability to link a single user to multiple devices such as phones, tablets, and laptops.
What is “Deterministic tracking”?
Cross-device linking based on the user logging in, so the same login is observed across devices.
What is “Probabilistic tracking”?
Cross-device linking based on inferences from sources like IP addresses, cookies, location, and behavioral data.