Version: (using KDE 4.4.0) Installed from: openSUSE RPMs Often when closing kmail the app window disappears but the kmail process remains running (forever). Also I get periodiacal messages kmail(18345) KMKernel::getFolder: Folder not found: "/Local" every five seconds. The process monitor also shows me three akonadi_maildir_resource processes a single akonadi_maildispatcher_agent and a kio_file targeting a kmail slave socket.
See this hint: http://userbase.kde.org/Akonadi#Folder_not_found:_.22.2FLocal.22 Does that resolve your problem ?
*** This bug has been marked as a duplicate of bug 228599 ***