Apple just doubled down on its contentious commissions policy by telling Hey's email creators to make payment changes to get back in the App Store

• Apple is locked in an escalating standoff with app developers who are upset that Apple takes a commission of up to 30% from all in-app purchases.
• This week, the creators of a new email app called Hey publicly slammed Apple as "gangsters" after Apple rejected Hey from the App Store. Hey creators said Apple was forcing it to recategorize its $99 annual subscription fee as an in-app purchase in order to take a cut of the profits.
• Apple doubled down in an email to Hey creators Thursday, saying the app would remain banned from the App Store until Hey reclassifies its $99 subscription fee as an in-app purchase.

Despite a public backlash from app developers, Apple isn't backing down on its controversial policy of siphoning up to 30% of revenue from apps that appear in Apple's App Store.

The tech giant was the target of heated criticism this week from Basecamp, an app maker that just released a new email app called Hey. Users of Hey must pay a $99 subscription fee, but the app initially guided users to make that payment outside the app to avoid Apple taking a commission. Apple banned Hey from its App Store as a result.

On Thursday, Apple doubled down on its policy. The company said in an email to Hey's creators that it would have to retool the app to let people buy subscriptions in-app before Apple would let it back into the App Store. The email was first reported by NBC News.

"We understand that Basecamp has developed a number of apps and many subsequent versions for the App Store for many years, and that the App Store has distributed millions of these apps to iOS users," the email reads.

Basecamp CTO David Heinemeier Hansson criticized Apple's decision in a tweet Thursday, calling the email "just more edicts from the monopoly king."

An Apple spokesperson did not immediately respond to a request for comment.

Apple's App Store has drawn scrutiny from regulators and lawmakers, who have criticized it as a monopoly where Apple can punish competitors without retribution. Rep. David Cicilline, chairman of the House Antitrust Subcommittee, told The Verge Thursday that Apple's commission amounts to "highway robbery." Apple is the defendant in a lawsuit filed by two app developers over its App Store policy enforcement.