There are three different formats  to an email on the Format Text tab:  HTML, Plain Text, or Rich Text formatting.  These different types of formatting can change the way a message displays, and Plain Text does not allow any formatting, such as bold, bullets or justification.

 

To change the format type, click the mouse inside the message area of the email and click the Format Text tab. The highlighted option under Format is the current format.  Click the option you want to use in your message.

 

When the format is changed after opening the reply, quote prefixes, signatures, colored text, and "mark my comment" are not added to the message. To use these features, change the message format in Actions > Edit Message then Format text tab before hitting Reply or ReplyAll.