Version: (using KDE 4.2.2) Installed from: Ubuntu Packages Spell checking in KMail (and other applications, too, but KMail is more wired and it's the only place I need it) acts quite wired for me (KDE 4.2.2, Kubuntu 9.04 RC): At the beginning, it wouldn't highlight any mistakes in the edit area, "Extras - Spell check" did nothing. While I continued setting up my system, it worked properly one time, before falling back to the old state. I recently discovered the configuration window at "Settings - spell checker" and saw it was set to "German", without any country being mentioned. I set it to "German (Germany)" after which both the context menu and the manual spell checking in the Extras menus worked fine, but wrong words are not underlined red. In addition, that setting is not saved, when I close the composer and open a new one, it always resets to the first entry on the list, which is sometimes "German" and sometimes "German (Austria)". I had to manually set it to "German (Germany)" each time I write a new message if I wanted to use spell checking, and that would still not give me the red underlines. The spell checker options in the system settings are completely ignored (which I think was the case from the beginning, but I did not check). Spell checking in Konqueror worked fine after I manually set the spell checker options once - they are correctly saved though. Konqueror, too, ignores the global spell checking options even when I manually remove the local ones from the konquerorrc file (in which case it defaults back to "German" and does not work until I set it to "German (Germany)" again, which will make "German" vanish from the list). What is wired though is that the spell checker in all applications also offers Turkish and Hebrew spell checking which I never installed. Choosing a non-German language will bring back the "German" entry to the list if it vanished. I'm sorry if this description sounds a bit confused, but that's exactly what I am and I could not find and reproducible pattern so far.
I found another application which can use spell checking: Kopete. It shows the same behaviour as the others, but does not have a spell checking options window so it can not be "repaired" by manually setting the language.
This bug is also in Launchpad: https://bugs.launchpad.net/ubuntu/+source/kdebase-workspace/+bug/365601 I can confirm what was written there, that when starting KMail directly spell checking in the message window works, but opening a new one still resets the options.
I now had the case that Konqueror also did not show the red lines even though the words were wrong (and the context menu offered corrections), so that bug does not seem to be KMail-specific.
KMail spell checking works fine by now, so this seems to be fixed