The third-party developers who have access to Gmail user data allegedly share them with marketers, hedge funds and other businesses.
Letting employees read user emails has become "common practice" for companies that collect this type of data, says Thede Loder, the former chief technology officer at eDataSource Inc., a rival to Return Path.
The companies that had spokespeople quoted in the article claim that all their employees must adhere to strict guidelines when checking user data, and while there are no signs of misuse amongst other developers, the potential is certainly there.
Last year, Google said that it will keep the privacy of its users paramount and would stop its computers from scanning the inboxes of Gmail users for information to personalize advertisements. Computers normally do the scanning, analyzing about 100 million emails a day. There's no doubt that some of the actions described, such as having employees read users' emails to train machine learning algorithms, are cause for alarm.
Using a service like Gmail puts you at the mercy of companies like Google. Google has since stopped that practice, but not everyone else did.
For those who might be concerned about this discovery, you can go to your Google Account's main page, head to the Sign-in & Security section and select "Apps with account access".
It pointed the BBC to its developer policies, which state: "There should be no surprises for Google users: hidden features, services, or actions that are inconsistent with the marketed goal of your application may lead Google to suspend your ability to access Google API Services".
However it isn't as nefarious as you might think as these scans were conducted using apps that users would have had to give permission to.
Google's mail service has always been criticized for the invasive practices of the company, which runs nearly entirely on employing all the data it collects on users to attract advertisers and target their wares to the people most likely to buy them.
Two third-party apps have come under particular scrutiny.