In brief: Blix, a developer of messaging products and software, has filed a lawsuit against Apple, claiming that Cupertino's "Sign in with Apple" feature infringes on patented technology powering the 'Share Email' feature on BlueMail, Blix's email client. The lawsuit also calls out Apple over its illegal monopolization of the App Store that it used to suppress BlueMail's presence on the storefront.

Apple's competitive practices are in the spotlight again as an app developer accuses the company of patent infringement and antitrust violations in a new lawsuit filed in Delaware's federal court, last Friday.

At its annual developers' conference, Apple introduced a new "Sign in with Apple" feature for iOS 13, an in-house authentication service meant to hide private user data and give users a quick, convenient way to sign into apps and websites. However, Ben Volach, co-founder of Blix, says that Apple stole it from his company's BlueMail app, particularly the "Share Email" feature that uses patented technology to communicate "using manageable public interaction addresses, without revealing their private interaction addresses."

Volach claims that Apple's new feature offers a similar service whereby customers can create new internet accounts using their Apple credentials, allowing email exchange without finding out the actual email address.

The "Share Email" feature was added to BlueMail in August 2018, one year after Volach had received a patent on the technology. "Not long after Mr. Volach's team unveiled BlueMail’s innovative anonymous communication options, Apple took Mr. Volach’s pioneering ideas—without permission, payment, or credit—and used those ideas in Apple’s own products," said the lawsuit.

The document further states Apple's lack of acknowledgement that the idea underpinning its "Sign in with Apple" feature was already in use in other software, and that days later, Cupertino also removed BlueMail from the MacOS App Store. This, Volach claims, was done to prevent his software from "readily reaching consumers and competing with Apple's own products," and not because of TypeApp, an app which Apple accused BlueMail of copying and caused the latter's removal, despite TypeApp being voluntarily taken off the store weeks before BlueMail launched.

According to the filing, BlueMail was artificially suppressed from appearing in the iOS App Store search results and once the issue was highlighted in a New York Times article, Apple adjusted its algorithms after which BlueMail's place in search results rose from 143 to 13.

Though it remains to be seen how things go from here, it's not the first time that Apple has been called out for unfairly using its dominance in providing a platform for apps and then putting out and favoring first-party competing services. A problem it addressed earlier this year when Spotify accused it of antitrust violations.