Microsoft Outlook offers three different message formats: plain text, HTML, and rich text. The main differences between these message formats relate to the way they handle images, characters such as bullet points, and styles such as bold.

The goal of any form of communication is for your message to be clearly understood. For that to happen, your recipient must be able to see it.

HTML: An email in HTML format will display all of the colors, positioning, fonts, styles, etc. that you used to create it, provided that your recipient has Outlook set up to receive emails in HTML format. Most users do; in fact, that's the default setting.

Plain Text: An email sent in plain text format contains only text characters. Plain text does not support bold, italics, colored fonts, or other text formats. It also does not support images displayed directly in the message body, although you can add images as attachments. This format ensures maximum compatibility; all email applications support plain text, and any email account can read your message.