Version:            (using KDE KDE 3.4.3)
Installed from:    Fedora RPMs
OS:                Linux

This is probably a useless crash report, as it happened while I wasn't paying attention to kmail. I was sorting my email (Still waiting on imap filter targets to get into my RPM repos...) by dragging multiple selections from folder to folder, when suddenly it crashed and I got the following report:
[KCrash handler]
#4  0x037d6c1e in KMFolder::createJob () from /usr/lib/libkmailprivate.so
#5  0x039b09fc in KMMainWidget::slotMsgSelected ()
   from /usr/lib/libkmailprivate.so
#6  0x039dd6f3 in KMMainWidget::qt_invoke () from /usr/lib/libkmailprivate.so
#7  0x071f9f44 in QObject::activate_signal ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#8  0x037870f0 in KMHeaders::selected () from /usr/lib/libkmailprivate.so
#9  0x037ce4c6 in KMHeaders::highlightMessage ()
   from /usr/lib/libkmailprivate.so
#10 0x037ce8b0 in KMHeaders::highlightMessage ()
   from /usr/lib/libkmailprivate.so
#11 0x039c36bd in KMHeaders::qt_invoke () from /usr/lib/libkmailprivate.so
#12 0x071f9f44 in QObject::activate_signal ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#13 0x0758640d in QListView::currentChanged ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#14 0x072e9f27 in QListView::setCurrentItem ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#15 0x072ee156 in QListView::contentsMousePressEventEx ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#16 0x072eeb48 in QListView::contentsMousePressEvent ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#17 0x051a6653 in KListView::contentsMousePressEvent ()
   from /usr/lib/libkdeui.so.4
#18 0x037ce9d6 in KMHeaders::contentsMousePressEvent ()
   from /usr/lib/libkmailprivate.so
#19 0x07321e53 in QScrollView::viewportMousePressEvent ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#20 0x0731ee50 in QScrollView::eventFilter ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#21 0x072e9387 in QListView::eventFilter ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#22 0x037ccd6b in KMHeaders::eventFilter () from /usr/lib/libkmailprivate.so
#23 0x071f99cc in QObject::activate_filters ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#24 0x071f9a41 in QObject::event () from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#25 0x07237e9c in QWidget::event () from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#26 0x0719517d in QApplication::internalNotify ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#27 0x071960df in QApplication::notify ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#28 0x04dea127 in KApplication::notify () from /usr/lib/libkdecore.so.4
#29 0x0712a756 in QETWidget::translateMouseEvent ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#30 0x07128f84 in QApplication::x11ProcessEvent ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#31 0x0713d6d8 in QEventLoop::processEvents ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#32 0x071ad8cb in QEventLoop::enterLoop ()
   from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#33 0x071ad7d6 in QEventLoop::exec () from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#34 0x07194b49 in QApplication::exec () from /usr/lib/qt-3.3/lib/libqt-mt.so.3
#35 0x0805a377 in ?? ()
#36 0x045a650f in __libc_start_main () from /lib/libc.so.6
#37 0x08057ec1 in ?? ()

I wish I could provide more info :/