Application that crashed: kmail
Version of the application: 1.12.4
KDE Version: 4.3.4 (KDE 4.3.4)
Qt Version: 4.5.3
Operating System: Linux 2.6.32-ARCH x86_64

What I was doing when the application crashed:
creating new folder
creating new filtering rules which moves to the new folder
applying the rule on every mails with Ctrl+A then Ctrl+J
-> crash

 -- Backtrace:
Application: KMail (kmail), signal: Segmentation fault
[KCrash Handler]
#5  0x0000000000000001 in ?? ()
#6  0x00007f64f175f7c2 in KMReaderWin::parseMsg(KMMessage*) () from /usr/lib/libkmailprivate.so.4
#7  0x00007f64f174d45a in KMReaderWin::displayMessage() () from /usr/lib/libkmailprivate.so.4
#8  0x00007f64f174d634 in KMReaderWin::updateReaderWin() () from /usr/lib/libkmailprivate.so.4
#9  0x00007f64f175a71d in KMReaderWin::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libkmailprivate.so.4
#10 0x00007f64f0f49d3c in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQtCore.so.4
#11 0x00007f64f0f43ce3 in QObject::event(QEvent*) () from /usr/lib/libQtCore.so.4
#12 0x00007f64f03e607c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#13 0x00007f64f03ed34e in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQtGui.so.4
#14 0x00007f64f25d68f6 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#15 0x00007f64f0f34bfc in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQtCore.so.4
#16 0x00007f64f0f603e2 in ?? () from /usr/lib/libQtCore.so.4
#17 0x00007f64f0f5d3f8 in ?? () from /usr/lib/libQtCore.so.4
#18 0x00007f64e7f8e26e in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#19 0x00007f64e7f91c28 in g_main_context_iterate () from /usr/lib/libglib-2.0.so.0
#20 0x00007f64e7f91d50 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#21 0x00007f64f0f5d123 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#22 0x00007f64f047914e in ?? () from /usr/lib/libQtGui.so.4
#23 0x00007f64f0f33532 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#24 0x00007f64f0f33904 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQtCore.so.4
#25 0x00007f64f0f35ab9 in QCoreApplication::exec() () from /usr/lib/libQtCore.so.4
#26 0x0000000000402f89 in _start ()

Reported using DrKonqi