With form regions, yes, you could, but that would be a very heavy solution
involving a fair bit of (simple) code.
As a workaround, you can use conditional formatting to change the color of
incoming mail items. I do this for people on my team (for instance, Doehee's
mail items show in pink, Bruce in blue, etc...)
Here's how: click view \ current view \ customize current view.
click the Automatic formatting
click the Add button
click Condition
now you will get a little UI that lets you choose which mail items you want
to work with. In this case, From == <<Sender email name>>
OK
now change the font to whatever color, size, etc... you want.
the downside is doing this for each person you want to create the color for.
But it is still simpler than the alternate method.
I hope this works.