email color problem

Here's a strange one for the experts! Outlook Express and Thunderbird.
Create new message, then try to change text color. No change shown, all
still in black, but..........prints out in color, If you look at the
source for the email. the html is correct, and when sent to someone,
displays in color, which makes me think it's a computer specific
problem, but... all other programs, e.g. Word, Wordperfect have no
problem, hmmm! I'm stumped