What's the difference? Your "folders" are all actually subfolders of the account's folder system. Ho hum. Anyway… Change the subfolder's name to make it unique - for example, add a numeral to it. This is so you don't get into a position where you try to generate two folders with the same name. Go to where you want your folder to be. Create it there. Copy the contents of the old subfolder to the new folder. '''Right-click|Move to''' is my preference. You ''can ''drag-and-drop with the mouse, but it gets messy if you accidentally drop somewhere else en route. You may be able to drag and drop the subfolder itself. If this is in an IMAP-connected email account, you may find that you are not allowed to create folders where you want. I have at least two accounts (one is roundcube, another is outlook/exchange) where all my self-defined folders are obliged to be subfolders of Inbox. This is a restriction imposed by the server configuration, and not a choice that you, I or Thunderbird can override.