Connection data is metadata generated when a device communicates with a server. It can include when a connection occurred and network details associated with the request. Unlike the contents of a message, this information describes how and when a service was accessed.
In email tracking, an embedded pixel can prompt a remote server request when a message is opened. The request may reveal connection data, helping a sender infer that an email was viewed and learn details about the interaction. Such telemetry can create privacy and compliance risks even when it does not expose message content. Defenders should inventory tracking features, limit collection to a clear purpose, and ensure applicable consent choices can be withdrawn effectively.