The U.S. government asked Yahoo to scan all incoming emails for a specific digital signature. The exact type of information sought was not disclosed, nor was the amount of data handed to US intelligence. The European Commission demanded further explanations about the Yahoo email scanning. Yahoo is not part of the Privacy Shield and the email scanning occurred before the discussion of the act was mooted. The first annual review is scheduled for this summer, with the participation of President-elect Donald Trump, the first of the first.”]
Source: https://www.bitdefender.com/blog/hotforsecurity/yahoo-email-scanning-explanations-rejected-by-eu/