Up until GroupWise 6.5, there were no facilities available to third parties that allowed the appearance of messages in a message list to be changed.
GroupWise 6.5 introduced category support, which allows you to change the color of items based on category. It would be possible to write an applet that assigned items to a particular item based on it’s official state, and have the color change accordingly. The same applies to message notes. (As message notes are custom fields, you can add the message note field to the message view and see the first line of the note in the client).
Another solution might be to build a custom message list view using Formativ portals. This option gives you full control over the view, but represents the most work.
I hope this information is useful.