Formatting
Message formatting

Use the HTML editor to compose messages
Use the plain text editor to compose messages

When sending HTML mail messages to recipients who are not listed as being able to receive them:

Ask me what to do if the message has HTML formatting, otherwise send plain text
Convert the message into plain text(may lose some formatting)
Send the message in HTML anyway(some recipients may not be able to read it)
Send the message in plain text and HTML(uses more disk space)
You can override these settings in any message through the options panel of the message composition window