MailBox: Creating Folders
You can create folders to store and organize your messages and files.
This can be very helpful for finding messages at a later time.
To do this:
Open your Mailbox.
Choose File > New > New Folder.
A new folder appears in the upper or left pane of your Mailbox window.
Name your folder by selecting it, then choosing File > Properties (Windows) or Get Info (Mac OS).
Type the new folder name in the field entitled Name.
Close the New Folder Info window and save your changes.
To move messages into a folder, drag them into the folder.
You cannot address messages directly to a folder, as you can to a conference.
Use View > Split to split your mailbox either vertically or horizontally
Here is an example of an organized mailbox with folders: