Hi John,
I do not have the same experience as you..when I enter text into the message box, it will be entered as RTF, and will be converted behind the scenes to HTML. There should not be a need to enter any HTML tags. If you want to add HTML tags, you can by clicking on the 'HTML" button in the toolbar.
Can you tell me what browser and version you are using as well as what operating system you have? This will help me in debugging the error you are experiencing.
Kevin