I wrote about this four years ago elsewhere. I just remembered it and posting it here for posterity (and for my own memory).
Original Date: March 20, 2006
Awhile back Lifehacker ran a post on how to highlight emails sent directly to you in Microsoft Outlook. Later, they showed how to “gray out” email not sent directly to you in Thunderbird. The latter option seems much more interesting to me. By using Outlook’s automatic formatting, the latter option can be replicated in Outlook.
Open up Outlook and go to Tools -> Organize. A pane similar to the one shown below will open. Choose “Using Colors” and turn on “Show messages sent only to me in [color].”
Then look for and click on “Automatic Formatting” (this can also be found in View -> Arrange By -> Current View -> Customize Current View) which will bring up a dialog box. Take a quick look at the rule Outlook just created–”Mail sent directly to me”–by clicking on it and then clicking “Condition…”. Under the “Advanced” tab you’ll see rules created for all your email addresses and names used in Outlook. Note these names because you’ll use them in a second.
Create a new rule by clicking “Add” and then clicking “Condition…”. Go to the “Advanced” tab and fill in information similar to what is shown below. The field should be “To” (or CC if you wish); the condition should be “doesn’t contain” and the value should be the names and email addresses you noted earlier.
Click “Ok” to return to the previous dialog box and click “Font…” to change the font color to a color of your choosing. Below is an example of how the new outlook may look.