Version: (using KDE 4.2.0) OS: Linux Installed from: Fedora RPMs After upgrading do KDE 4.2, KMail does not group messages in threads anymore. Also, the option to set this up has gone from the Folder menu. What happened? This feature is too much important to be gone... For anyone who subscribes to lists with high traffic, there's no use for a mail client that can't thread discussions.
The view in KMail was reworked for KDE4.2 and I can ensure you that the thread option is available. Look at http://nowwhatthe.blogspot.com/2008/11/hero-of-today.html And http://2.bp.blogspot.com/_uykUGdiPttw/SR7QOc-sJMI/AAAAAAAAAO4/lYiKd2pCtXs/s400/kmail06.png
Just look at the bottons at the right of the quick search field, they configure how the message list is shown (remembered per message list tab).
Thanks very much. I found it now and It's really a relief. Sorry for the invalid bug.