Kmail -- offline mode

Hello everyone, as of recently when kmail is started a dialog pops up which says that kmail is in offline mode and asks whether I would like to switch to online mode. I don't know where this comes from, but I guess it may have something to do with some dbus- or notification-related package I have removed some time ago. But why would kmail notify being in offline mode everytime it gets started though I never switched to offline mode before?! Any hints about where to look at to investigate further are welcome. Regards, Stefan