Version: (using KDE 4.2.4) Installed from: Debian testing/unstable Packages I get error messages "IMAP connection timed out" every now and then. I don't care much about them, because I still can read my mail, but these messages are extremely annoying, because they steal focus from the compose window when writing mail.
You should try to setup the Focus stealing prevention level to Normal or higher until those messages goes to the new Notification system.
Just tried it in KDE 4.4.0 and it goes through the new system and does not steal focus anymore