I think--and this is just supposition on my part--that KotoR's idea of "new" mirrors that of Internet Explorer: any message you haven't read yet remains bold-faced and new. So if you want to remove old items that are still regarded as new in KotoR, you have to click on 'em, and look at each.
Annoying, I know. Why they couldn't have added an alphabetical sort while they were including everything else this side of existence, I'll never know.
