iOS 15.4 has an interesting Hidden Mail feature that helps you organize your folder

Apple’s iOS 15.4 and iPadOS 15.4 updates have surprised iCloud Mail users and anyone using the Mail app as their primary email client for AOL, Gmail, Outlook, Yahoo, and other third-party email services.

When you’re in the main Mailboxes view in the Apple Mail app on your iPhone or iPad, you can scroll down to the first section, which contains your mailboxes and any filters you’ve added, to take a closer look at each email account.

Clicking on an account will expand the directories, giving you quick access to drafts, sent mail, junk mail, trash, archives, and all your custom folders and shortcuts. However, it literally expands everything, making it difficult to scroll to the directory you want.

Prior to version 15.4, if you had folders with subfolders, those subdirectories would appear whether you wanted them to or not. The gray expand arrow next to the parent directory was useless, so clicking it didn’t collapse the child folders.

With iOS 15.4 and iPadOS 15.4, released March 14, 2022, you can now collapse every folder tree you see. It will remember your preferences so you don’t have to worry about auto-expanding them the next time you go to check. This is something Apple should have added years ago, but better late than never.

It would be nice if Apple included an actual setting in Mail’s settings to auto-collapse or auto-expand everything in the email account’s directory hierarchy, but the new minimize and expand buttons are the next best thing.