Thousands of private emails have allegedly been read by staff at third party companies with access to people's Gmail accounts.
A bombshell report from the Wall Street Journal has detailed what one company called Google's "dirty secret".
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Google has confirmed to the journal that Gmail accounts can be accessed by third-party developers, who could then give staff members permission to access and read people's emails.
When connecting a Gmail account with an external management, users are asked to grant permissions which can include the ability to read, send, delete and manage your email.
Several companies told the Wall Street Journal that their employees had read "thousands" of emails, and had not asked those users for specific permission.
Google told the journal only companies it approved could access emails, and only if users had granted specific permission.
It said users could go to the Security Check-up page to check which apps could access their data and could revoke access if they wanted to.