This 2015 article at TapSmart, that explains it in terms of deleting all messages in a folder. (This is the best trick I’ve learned about in iOS Mail in years, and a big hat tip to It’s easy if you use a set of actions that Apple doesn’t document, but will save you an enormous amount of time-you don’t have to select each message individually. However, you can move all this email to an IMAP-supporting email account. This has left a gap for people either using POP3 or local storage for some of their IMAP special folders because if you have a sudden device failure, need to restore a phone or tablet from a backup, or want to migrate from one device to another, this locally stored email is lost. Since your Mail attachment downloads are saved in a local system folder on Mac, you can delete local copies of saved email attachments through Finder. (See Settings > Passwords & Accounts > your mail account > Account > Advanced, and tap any item under Mailbox Behaviors.) You can opt to configure iOS so that any or all of your Drafts, Deleted, and Archive folders are stored locally on a device.

To launch the Files app, swipe one finger downward from the middle of the Home screen to open Spotlight Search, type Files into the search bar, then select Files.

Mail largely remains on the server, with some exceptions. To find downloads on your iPhone or iPad, you must open the Files app, select the Browse tab, and navigate to iCloud Drive > Downloads.

Apple mail download folder