You can change the appearance of your outgoing mail by using one of Outlook's built-in themes or stationery to better reflect the nature of your business. Themes include a background and text formatting, while stationeries contain only a background.
As you compose your message, you can use the text styles assigned to your theme simply by selecting them as you go.
While composing a message, click the Format Text tab.
Open the Styles gallery, if necessary.
Depending on how big the message window is, the styles gallery may appear on the ribbon, or be condensed into a menu that appears when you click the Styles button.
Every theme will use the same style names but will use its own set of colors and fonts.
Select a style.
Now just enter the text and it will appear in the theme style that you selected.