I doubt it was Google itself – Google is a one-way sieve when it comes to data. Google allows advertisers to tap into their user graph for targeting and attribu

I doubt it was Google itself – Google is a one-way sieve when it comes to data. Google allows advertisers to tap into their user graph for targeting and attribution, but they don't actually give access to user-level info in any meaningful form, let alone in a form that would allow you to get your hands on user emails. The closest you can get is Ads Data Hub[1], which requires advertisers to import their first party data into the (very expensive) Google-controlled environment to work, and is designed so that Google's identifiers can be used for joins and aggregate functions but can't be directly returned in queries. There are providers that directly exploit their graph by selling the PII within it, such as GetEmails[2] (and the publishers they source data from). But Google isn't one of them. [1] https://developers.google.com/ads-data-hub https://developers.google.com/ads-data-hub [2] https://martech.zone/getemails-identify-anonymous-visitors/ https://martech.zone/getemails-identify-anonymous-visitors/