Apologies. It seems that I forgot to switch on list management in kmail. I've re-sent the message, this time to the list. It should arrive along with this.
In kmail, are you using disconnected IMAP? A snippet from an email I sent to the Alpine (email client) list: (the last two links are the most interesting)
I've never seen kmail mentioned in a positive context. Its maildir support is broken (doesn't follow the same naming rules as most MTAs/MDAs for subfolders. Not a "real" standard, but it is a de facto standard), and it eats IMAP mail. At the least, warn your correspondent to stay away from kmail's "disconnected IMAP" feature:
[1] http://lists.kde.org/?l=kdepim-users&m=113877863022834&w=2 [2] https://bugs.launchpad.net/kdepim/+bug/61155 [3] https://bugs.kde.org/show_bug.cgi?id=134292 [4] https://bugs.kde.org/show_bug.cgi?id=104956