Version:           0.50.50 (using 4.00.67 (KDE 4.0.67 >= 20080325), Gentoo)
Compiler:          x86_64-pc-linux-gnu-gcc
OS:                Linux (x86_64) release 2.6.24-gentoo-r3

I tried migrating to kmail, I imported my local mail folder, and tried to remark in kmail the spam messages. I used bogofilter, byt he way. Clicking "spam" on all the 34 messages( not exact number) crashed kmail. Backtrace: 
Application: KMail (kmail), signal SIGSEGV
[Thread debugging using libthread_db enabled]
[New Thread 0x2b03e5887500 (LWP 24816)]
[New Thread 0x40800950 (LWP 24830)]
[KCrash handler]
#5  0x00002b03d69578d5 in KMMetaFilterActionCommand::start (this=0xba53a0)
    at /var/tmp/paludis/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/kmcommands.cpp:1773
#6  0x00002b03d69579a5 in KMMetaFilterActionCommand::qt_metacall (
    this=0xba53a0, _c=QMetaObject::InvokeMetaMethod, _id=6750305,
    _a=<value optimized out>)
    at /var/tmp/paludis/kde-base/kdepim-9999.4/work/kdepim_build/kmail/kmcommands.moc:1460
#7  0x00002b03d4f3d4b2 in QMetaObject::activate (sender=0xa728b0,
    from_signal_index=<value optimized out>, to_signal_index=6, argv=0x41)
    at kernel/qobject.cpp:2995
#8  0x00002b03df8c24c7 in QAction::triggered (this=0x8bdde0, _t1=false)
    at .moc/debug-shared/moc_qaction.cpp:216
#9  0x00002b03df8c3090 in QAction::activate (this=0xa728b0,
    event=<value optimized out>) at kernel/qaction.cpp:1129
#10 0x00002b03dfbf4104 in QAbstractButtonPrivate::click (this=0xba2550)
    at widgets/qabstractbutton.cpp:529
#11 0x00002b03dfbf4371 in QAbstractButton::mouseReleaseEvent (this=0xba2510,
    e=0x7fffd5edf430) at widgets/qabstractbutton.cpp:1116
#12 0x00002b03dfcc1d6a in QToolButton::mouseReleaseEvent (this=0x8bdde0,
    e=0x0) at widgets/qtoolbutton.cpp:675
#13 0x00002b03df91cb53 in QWidget::event (this=0xba2510, event=0x7fffd5edf430)
    at kernel/qwidget.cpp:6850
#14 0x00002b03dfbf2e30 in QAbstractButton::event (this=0xba2510, e=0x0)
    at widgets/qabstractbutton.cpp:1078
#15 0x00002b03dfcc1aa9 in QToolButton::event (this=0x8bdde0, e=0x0)
    at widgets/qtoolbutton.cpp:1105
#16 0x00002b03df8c8f6f in QApplicationPrivate::notify_helper (this=0x62f3e0,
    receiver=0xba2510, e=0x7fffd5edf430) at kernel/qapplication.cpp:3735
#17 0x00002b03df8cb915 in QApplication::notify (this=<value optimized out>,
    receiver=0xba2510, e=0x7fffd5edf430) at kernel/qapplication.cpp:3464
#18 0x00002b03d9e3229e in KApplication::notify (this=0x7fffd5edfed0,
    receiver=0xba2510, event=0x7fffd5edf430)
    at /var/tmp/paludis/kde-base/kdelibs-9999.4/work/kdelibs-9999.4/kdeui/kernel/kapplication.cpp:311
#19 0x00002b03d4f28338 in QCoreApplication::notifyInternal (this=)
    at kernel/qcoreapplication.cpp:586