Currently subscribed folders are listed in the colored area to the left. This frame may be set to automatically refresh in the Options page. At the top of the left frame is large and bolded heading. If changes have been made to the subscribed folders using the folders menu item, this list can be refreshed with the link below the title. Oddly enough, this link is titled "refresh folder list".
The first folder listed contains received mail. To the right of the first folder is a number in parenthesis "( )" reflecting the count of unread emails. This number is likely to vary from the total number of emails displayed in the right frame. Under the main folder are likely to be other folders or subfolders. Colors for these folders will change with theme choices made in the options page.
You may delete any folder displayed in the drop down list box to the left of the Delete button. Notice that this list may not include all the folders displayed. The special folders such as your sent or your trash folder cannot be deleted, and of course, you cannot delete INBOX.
Folders may be created by simply typing the desired name into the text box and pressing the Create button. If you wish that this folder be a subfolder of another one, you can choose that in the drop-down box with the list of folders.
On some mail servers, there are two types of folders. One that contains messages, and one that contains folders. You may see an option called "Let this folder contain subfolders." If you do and you check that, the folder you create will only be able to contain folders and not any messages. Otherwise, you will only be able to store messages in it and not folders.
You may rename any folder displayed in the drop down list box to the left of the Rename button. Notice that this list may not include all the folders displayed in the left frame. For obvious reasons, you cannot rename the sent, trash, or INBOX folders.
You may choose as many folders as you wish from either the subscribe or the unsubscribe box, then click the button under the box to make the action take effect. You will notice that the folders move to the other box. You can then re-subscribe to them, or unsubscribe again as you wish.