You can customize the look and feel of the Web interface of SUmail to better suit your personal style. To select one of the pre-configured themes in SUmail, do the following:
Clicking the Gear icon (Settings) located between the Bell and and the Question Mark on the top right corner of your screen.
Click "Theme." Next, click on the desired layout out of the given theme choices. When you have found the preferred theme, click on it. The top toolbar will immediately display using the new theme.