Information about the people contacted was collected and analyzed, it's a study fundamentally about how they react to this email, it is not (just) about a third party. In the case of websites run by a single individual (such as OP) there is no third party at all, but in all cases information about the first party was being collected and analyzed.
To be a bit more pithy, here is one example of such an analysis (admittedly, I'm not sure comments on twitter count): https://twitter.com/RossTeixeira/status/1471249559879929861