if your sending HTML it is possible otherwise perhaps not.

when writing an email is there a toolbar between the message your typing and the subject line with Body 'Text as the fist entry. If so that is followed by a font name and then a colour picker.

Thank you, this will change the color of the font, but I'm trying to highlight a portion of the text, not change the font color.

That control provides setting for foreground and background(left square / Right square). If your unable to highlight using either of those options, perhaps you could explain to me what highlighting is.

Highlighting is as if you took a marker and passed it across a printed page, "highlighting" one or several lines (or on a map highlighting the route you were going to follow). If I am correct, one square changes the color of the letters and the other changes the color of the background. I have not been able to change the background of one word or one or several lines, which I would like to accomplish, if possible. Thanx.

This is about as sophisticated as it gets. http://kb.mozillazine.org/Highlighting_in_messages

Thank you very much!! Ron