macOS Mojave Mail icon 300x300macOS Mail folders are often not sorted in alphabetical order by default, especially when new mailbox folders are added to an existing mailbox. Although the mailbox folders are in A to Z order at the mail web access, e.g. iCloud.com, they are not on your macOS Mail app. If you are unable to order alphabetically all mailbox folders on your Mac, you just need to delete the corresponding mailbox library. Not a single SSH shell command is necessary.