When you write a new e-mail in Evolution, it is by default not formatted. You see this partly because the setting 'Basic Text' is disabled. This is often an appropriate choice because many do not like / read formatted e-mail
If you want to compose formatted e-mails, you may select HTML from the Format menu or from the shortcut menu under the Subject field. The menu bar for formatting will now be enabled and you can format text in your email.
