Mail (Yosemite): Favorites bar

The Mail Favorites bar provides quick access to your favorite or most-used mailboxes or folders.

• Show or hide the Favorites bar:
  Choose View > Show Favorites Bar or View > Hide Favorites Bar.
• Add items to the Favorites bar:
  Drag a mailbox from the Mail sidebar to the Favorites bar. Mail doesn’t move the mailbox; it adds an alias for it to the Favorites bar.
• Remove items from the Favorites bar:
  Drag an item from the Favorites bar. Visual and sound effects indicate it has been removed.