The big picture: How tech companies snoop through your messages

Internet giants are letting software app developers scan through their email users’ inboxes when they’ve signed up for email-based services such as shopping price comparison services, WSJ reports.

Why it matters: The common practice is supposed to make software algorithms better so they can function better for users — but the users don’t appear to be made aware their emails are being read or asked if they would sign off on that in the first place. And companies that have said they’re not using this practice anymore still are.

Gmail said last year it was nixing a similar feature that scanned inboxes to personalize ads to hold "privacy and security paramount" — but it hasn’t followed through.

The details: Return Path, Inc., has computers analyze about 100 million emails per day. People who have accounts with Return Path and who use Microsoft, Yahoo, and Gmail for email are all impacted. Return Path read about 8,000 un-redacted emails for training purposes as well. Edison Software, a Gmail developer, scanned emails in a similar way.

What they're saying: Neither Return Path nor Edison asks users if hey could read emails. Oath said access to email is decided "on a case-by-case basis" and requires "express consent." Microsoft says its terms of use prevent developers from accessing data without consent.

• Gmail said "before a non-Google app is able to access your data, we show a permissions screen that clearly shows the types of data the app can access and how it can use that data."