Outlook provides several formatting options to make your email messages look professional. Add colors to your greetings, underline or highlight key points, or use the Office Photo Browser to quickly add your iPhoto or Photo Booth images to messages.
If these options in Outlook are insufficient for your needs, compose your messages in Word and then transfer the contents to Outlook by using the File -> Share -> E-mail (as HTML) option. All formatting-including your tables, charts, and fonts- is preserved in Outlook.
Make sure you set Outlook as your default mail application when using it with other applications. In Outlook > Preferences > General, enable the Make Outlook the default application for e-mail, contacts, and calendar option.
Keep in mind
Rich formatting, with colors, fonts, images, and hyperlinks, does not always translate well when converted to Plain text formatting. Plain text is just black and white text with no formatting applied to it. One of the notable advantages of Plain text is the small message size, which is why several companies use it as the default messaging format or convert to this type for messages received from outside their company. If you are using rich formatting, for example, white text with colored background, the background gets converted to white when received in Plain text. White text on white background will probably not mean much to your receiver.
Also, if you are embedding images in your email, watch the resulting email size. ISPs set message limits and large emails usually bounce back. Check out my earlier post on how to avoid bounced messages by reducing the attachment size.