Color
causes the affected text to be displayed in a specified
color. The "color" command requires a parameter that is
specified by using the "param" command. The parameter
data can be one of the following:
red
blue
green
yellow
cyan
magenta
black
white
or an RGB color value in the form:
####,####,####
where '#' is a hexadecimal digit '0' through '9', 'A'
through 'F', or 'a' through 'f'. The three 4-digit
hexadecimal values are the RGB values for red, green, and
blue respectively, where each component is expressed as
an unsigned value between 0 (0000) and 65535 (FFFF). The
default color for the message is unspecified, though
black is a common choice in many environments. When
nested, the inner "color" command takes precedence.
In fact, you have even more options, not just two:
1) RGB: #rrggbb (rgb hex) / rgb(r,g,b) (rgb int 0-255) / rgba(r,g,b,a) (as before, plus alpha). In addition, rgb/rgba support percentage values instead of 0-255.
2) red (color names)
3) hsl(h,s,l)
4) cmyk(c,m,y,k)
For compatibility with anything except Thunderbird (which supports all four formats IIRC), stick with #rrggbb or plaintext names. Webmailers are especially prone to filtering by regex (ugh), and stripping out everything they don't know.
Odd that it's 96bpp colour, of all things.