If it is a business-related email, simpler is better. But if it's a social email to a friend, there's nothing wrong with using decorative backgrounds and fancy fonts,
as long as the recipient is able to read it. If they don't have the same fonts installed, they might just get a row of boxes or other gibberish.
I must admit, I'm one of those who loves pretty stationary, elegant fonts and different colored typefaces, which tries the patience of my much more traditional and straight-to-the-point husband.
