On the Mailbox Summary page, the Message Count shows the total number of messages in each mailbox; in addition, it also shows the number of new (unread) messages for the Main mailbox. You can set up Web Messaging to show the new message count for only the "Main" mailbox, or for all mailboxes. (Note that counting new messages for all mailboxes may take a while if you keep many messages in your mailboxes.)
Select Edit My Preferences under Personal Account Options.
On the Edit Preferences page, locate Show new messages for and select Main mailbox only or All mailboxes.
Click the Save button.