Version: (using KDE 4.4.2) Installed from: Ubuntu Packages Put both (akregator and kmail) to the system try by setting this in their sepcific preferences dialogs. Now go to the system tray settings and try to always hide one of them. You don't know which one is which - because both are named "kontact". It would be nice to see the real application name there. (I also reported this bug to plasma but no one pays attention there, maybe its more related to kontact, how it sends the sub-apps to the tray.)
*** This bug has been marked as a duplicate of bug 219197 ***