You can get some statistics from Google at https://transparencyreport.google.com/safer-email/overview https://transparencyreport.google.com/safer-email/overview

You can get some statistics from Google at https://transparencyreport.google.com/safer-email/overview https://transparencyreport.google.com/safer-email/overview They're a lot better than I thought! (over 90% in each direction, although no data here about certificate verification and the presence or absence of backbone downgrade attacks) If you run your own mail service, check out my colleague's project at https://starttls-everywhere.org/ https://starttls-everywhere.org/