On the left side you see a hierarchical list of all folders in your mailbox. Folders can be used to file email messages by topic, sender or whatever you choose for organization.
Incoming messages usually appear in the Inbox folder which is the first item in the folder list. There are some special folders which are used by the system to store sent (Sent) or deleted (Trash) messages and where not-yet-sent message drafts (Drafts) are saved. These system folders are indicated with special icons.
The number of unread messages in each folder is displayed at the right border of the folder list.
Click a folder in the list to show the contained messages in the message list on the right. The currently selected folder is highlighted in the list.
Folders with hidden subfolders are indicated with a small [+] icon which can be clocked to expand or collapse the folder tree.