An unknown number of web sites are leaking user data to third-party advertising and analytics companies, says Zach Edwards from Victory Medium, a company offering web analytics and testing systems. Websites mentioned in the report include Quibi.com, JetBlue.com and Mailchimp s Mandrill.com. The data went to at least Google, Facebook, Twitter, Mixpanel, Wistia, CrazyEgg, New Relic, DrawBridge. In some cases, email data is leaked to dozens of such service.
Source: https://www.bleepingcomputer.com/news/security/numerous-sites-leak-user-emails-to-advertising-analytics-services/