Show or hide the main toolbar in Mac Mail
When you are inside Mac Mail, the main toolbar will by default be visible, which is also the case in the new email window; if you are using keyboard shortcuts anyway, or accessing common commands from the menu system, toolbars just take up space (although they do add a pleasing touch of color to your email program). In this tutorial, we will show you how to show or hide the email toolbar in Apple Mail.
Toggle the Mail toolbar visibility On or Off
- When you are inside Mac Mail, the very top edge of the window will contain the usual controls on the left corner to close the active window, minimize it, or maximize it. The title of the window is in the middle, and towards the right edge of the screen is a "toggle" button, which mostly goes unnoticed unless you know to look for it. This button is not unique to Apple Mail, and many applications that use a toolbar will also use this convention. Click on the show / hide button as shown below:

- As soon as you do, Mac Mail will slide the email toolbar out of view: you can now see more of your email messages and program interface; just drag the bottom right corner of the window if you want to make it take advantage of the extra screen real estate it now has (if your main Mail window was maximized, you will now see a bit of space below the bottom edge of that window).
This is all you need to do to show or hide the main toolbar in Apple Mail on Mac OS X; note that this is a "persistent" setting, meaning that Mac Mail will remember your last preference after you've applied it, even after you restart the program.
Tip: it is also possible to achieve the same effect by clicking on the View menu, and choosing "Show Toolbar" / "Hide Toolbar", as appropriate (the same menu item reads one version or the other, depending on your current visibility of your main toolbar in the email program).