They are not tabs. They are buttons on a toolbar, or menu items on a menu. Hold down the alt key to make a menu visible. Press v on the keyboard or click on '''View''' in the menu to see options for toolbars, and select, at the least, '''Mail Toolbar'''. I'd also select '''Menu Bar''', since I like traditional menus, and 99.99% of the help on the web refers to these old fashioned menus. You my need to repeat this procedure in other windows such as the Compose window, the Calendar window and the Address Book window, which also have "optional" toolbars and menus.