An email app developer that's been at odds with Apple says the iPhone maker stonewalled its app update for weeks

• Blix, which has filed a lawsuit against Apple in the past accusing it of infringing on its technology, says Apple delayed approving an update to its BlueMail app for weeks.
• According to emails reviewed by Business Insider, Apple rejected Blix's app update for not including Apple's "Sign in with Apple" feature, a requirement for apps that offer a sign in option from another service.
• Since Blix is an email app, it should have been exempt from that rule.
• The interaction comes as some developers have been at odds with Apple over its policies, such as its requirement that app makers use Apple's in-app payment feature.

The company behind the popular email app BlueMail says Apple stonewalled its app updates after it criticized the iPhone maker.

In emails reviewed by Business Insider, Apple tells the developer, Blix, that it had rejected its app updates in part because of BlueMail's lack of a "Sign in with Apple" feature. Rejecting Blix's app updates meant BlueMail had not been up-to-date for its users since July 30.

The "Sign in with Apple" feature is also at the heart of a lawsuit Blix filed against the iPhone maker last year, accusing Apple of infringing on its patent for a similar feature. Blix is a frequent Apple combatant, and has also accused the tech giant of suppressing BlueMail, which competes with Apple's Mail app, in the App Store.

Apple later approved the update on Monday after reached for comment by Business Insider. The company pointed to the fact that BlueMail is approved and available in the App Store without "Sign in with Apple" functionality in alignment with its App Store guidelines.

Still, after six weeks in limbo, the BlueMail delay is the latest instance of an app developer raising concerns about how Apple interprets and enforces its App Store policies. That's important because Apple's management of the App Store has been under scrutiny in recent months as some major app makers have rallied against the tech giant, saying it implements policies that benefit Apple while hurting developers.

Companies like Spotify, Epic Games, and Tinder-parent Match Group have recently argued Apple's rules and policies have made it difficult for apps to compete in the App Store — in which Apple is both the operator and a competitor. In one of the most high-profile clashes yet, Apple has been locked in a legal battle with Epic Games over its removal of "Fortnite" from the App Store because the game maker attempted to skirt Apple's in-app payments system.

Blix cofounder Ben Volach also took these concerns to the EU's antitrust chief, Margrethe Vestager, in a September 21 letter. "The App Store is not a level playing field; developers are not treated equally when they compete with Apple's own apps," Volach wrote in the letter, which Business Insider has viewed.

Shortly after Business Insider reached out to Apple for comment on Blix's concerns, BlueMail's app updates were suddenly approved, Volach told Business Insider on Monday. Volach said the company did not make any changes to its submitted app update, nor appeal any of Apple's rejections, since receiving a rejection from Apple on September 15.

In emails dated August 13, August 15, and September 15, Apple told Blix it "must offer Sign in with Apple." In the first two emails from mid-August, Apple also cited a performance issue with the app in which the page would load indefinitely when logging in. The third email dated September 15 cited only section 4.8 of its app design guideline, a specific rule regarding "Sign in with Apple."

Apple has been transparent about requiring "Sign in with Apple" support if an app offers other social login options. The issue, however, involves an exception listed in Apple's guidelines that exempts apps that are a client for a specific third-party service and users are required to sign into their email or social media account directly to access their content.

BlueMail fits this description since it's an email app that requires users to sign in to their email account. BlueMail offers "Sign in with Google" to enable Gmail users to more easily login and access their Google account information through the app.

Blix's most recent experience with Apple also comes as app makers are more prominently voicing their concerns about the App Store. A group of developers that includes Blix, Epic Games, Spotify, Match Group, and Basecamp recently formed an advocacy group called the Coalition for App Fairness. These app makers and others have recently raised questions over how Apple implements its App Store policies.

In June, David Heinemeier Hansson, CTO and cofounder of Basecamp, criticized Apple after it initially rejected an app update because it did not support Apple's in-app payment system, of which Apple takes up to a 30% cut.

The episode created confusion among developers and app creators, which raised questions about why some apps are required to use Apple's in-app purchasing system while others, like Amazon's, aren't.

Documents released in July as part of a congressional investigation into Big Tech showed that Apple's deal with Amazon to get the Prime video app in the App Store required only a 15% commission even though Apple typically takes a 30% cut from subscriptions during their first year.

In his testimony at that hearing, Apple CEO Tim Cook said the company treats every developer the same and abides by "open and transparent rules."

But some app makers have pushed back on these comments, like Justin Payeur, president and cofounder of National Education Technologies, which makes a parental control app called Boomerang.

"To say that [the App Store] is a vibrant, competitive environment is just not true," Payeur told Business Insider in July.

Apple has also made some developer-friendly changes in recent months. In July, the company announced that it would allow developers to appeal violations of App Store guidelines. Apple is also temporarily waiving the 30% cut it usually takes from in-app payments for businesses that are holding paid events online via platforms like Facebook or ClassPass because of the pandemic.