Version:            (using KDE 4.3.2)
Installed from:    Ubuntu Packages

I just marked a message as important the first time. And I was astonished to find the message marked green(!). And also the icon at the beginning of the line, did not change, which would have been something I would expect.
I am aware that it is possible to change the colour manually. But I believe there should be sane defaults. First that would be changing the icon into that which is presented in the menu when you choose "mark as important" (which is the one akregator uses for the same purpose). Secoundly the colour should not be green. I am not sure what I would suggest, but may be inverted green. May be usability people know what is best.
Third (may be this would be a separate wish, tell me if it is necessary): How messages should be marked should be shared between apps like mailody, akgregator, kmail (and possibly others) like the places toolbar is shared in the filedialogue. Meaning there should be a general setting for all apps, which can be changed also on per app basis.