Application: kmail (1.13.5)
KDE Platform Version: 4.4.5 (KDE 4.4.5)
Qt Version: 4.6.3
Operating System: Linux 2.6.39-bpo.2-amd64 x86_64
Distribution: Debian GNU/Linux 6.0.3 (squeeze)

-- Information about the crash:
I marked few mails for deletion and clicked icon.Then I switched to another desktop and I got the pop-up window with the crash info.
This is on Debian 6 

 -- Backtrace:
Application: KMail (kmail), signal: Segmentation fault
The current source language is "auto; currently asm".
[KCrash Handler]
#5  0x00007ffbe1eb9250 in vtable for QX11PaintEnginePrivate () from /usr/lib/libQtGui.so.4
#6  0x00007ffbe283ce7d in KMMessage::transferInProgress (this=0x39157a0) at ../../kmail/kmmessage.cpp:271
#7  0x00007ffbe2b22900 in KMail::ImapJob::slotGetMessageResult (this=0x3635c90, job=0x3633770) at ../../kmail/imapjob.cpp:374
#8  0x00007ffbe2b24a2b in KMail::ImapJob::qt_metacall (this=0x3635c90, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff36125be0) at ./imapjob.moc:88
#9  0x00007ffbe20842e6 in QMetaObject::activate (sender=0x3633770, m=<value optimized out>, local_signal_index=<value optimized out>, argv=0xffffffffffd94978) at kernel/qobject.cpp:3295
#10 0x00007ffbe33dd802 in KJob::result (this=0x39157a0, _t1=0x3633770) at ./kjob.moc:194
#11 0x00007ffbe33ddaa0 in KJob::emitResult (this=0x3633770) at ../../kdecore/jobs/kjob.cpp:312
#12 0x00007ffbde0d53e3 in KIO::SimpleJob::slotFinished (this=0x3633770) at ../../kio/kio/job.cpp:517
#13 0x00007ffbde0d5da7 in KIO::TransferJob::slotFinished (this=0x3633770) at ../../kio/kio/job.cpp:1097
#14 0x00007ffbde0d3451 in KIO::TransferJob::qt_metacall (this=0x3633770, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff36125ff0) at ./jobclasses.moc:367
#15 0x00007ffbe20842e6 in QMetaObject::activate (sender=0x2fc5910, m=<value optimized out>, local_signal_index=<value optimized out>, argv=0xffffffffffd94978) at kernel/qobject.cpp:3295
#16 0x00007ffbde196b51 in KIO::SlaveInterface::dispatch (this=0x2fc5910, _cmd=104, rawdata=...) at ../../kio/kio/slaveinterface.cpp:175
#17 0x00007ffbde193ec3 in KIO::SlaveInterface::dispatch (this=0x2fc5910) at ../../kio/kio/slaveinterface.cpp:91
#18 0x00007ffbde188336 in KIO::Slave::gotInput (this=0x2fc5910) at ../../kio/kio/slave.cpp:324
#19 0x00007ffbde18851c in KIO::Slave::qt_metacall (this=0x2fc5910, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff36126410) at ./slave.moc:82
#20 0x00007ffbe20842e6 in QMetaObject::activate (sender=0x2fab7a0, m=<value optimized out>, local_signal_index=<value optimized out>, argv=0xffffffffffd94978) at kernel/qobject.cpp:3295
#21 0x00007ffbde0a3c67 in KIO::ConnectionPrivate::dequeue (this=0x2e19050) at ../../kio/kio/connection.cpp:82
#22 0x00007ffbde0a3d8d in KIO::Connection::qt_metacall (this=0x2fab7a0, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x3440430) at ./connection.moc:79
#23 0x00007ffbe2080e29 in QObject::event (this=0x2fab7a0, e=0x35f19d0) at kernel/qobject.cpp:1248
#24 0x00007ffbe141132c in QApplicationPrivate::notify_helper (this=0x22fecf0, receiver=0x2fab7a0, e=0x35f19d0) at kernel/qapplication.cpp:4302
#25 0x00007ffbe141780b in QApplication::notify (this=0x7fff36127030, receiver=0x2fab7a0, e=0x35f19d0) at kernel/qapplication.cpp:4185
#26 0x00007ffbe39ac796 in KApplication::notify (this=0x7fff36127030, receiver=0x2fab7a0, event=0x35f19d0) at ../../kdeui/kernel/kapplication.cpp:302
#27 0x00007ffbe207109c in QCoreApplication::notifyInternal (this=0x7fff36127030, receiver=0x2fab7a0, event=0x35f19d0) at kernel/qcoreapplication.cpp:726
#28 0x00007ffbe2074744 in QCoreApplication::sendEvent (receiver=0x0, event_type=<value optimized out>, data=0x22b6020) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#29 QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=<value optimized out>, data=0x22b6020) at kernel/qcoreapplication.cpp:1367
#30 0x00007ffbe209ab73 in QCoreApplication::sendPostedEvents (s=<value optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:220
#31 postEventSourceDispatch (s=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:276
#32 0x00007ffbd86536f2 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#33 0x00007ffbd8657568 in ?? () from /lib/libglib-2.0.so.0
#34 0x00007ffbd865771c in g_main_context_iteration () from /lib/libglib-2.0.so.0
#35 0x00007ffbe209a6b3 in QEventDispatcherGlib::processEvents (this=0x22ed4a0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:412
#36 0x00007ffbe14c119e in QGuiEventDispatcherGlib::processEvents (this=0x39157a0, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#37 0x00007ffbe206f9c2 in QEventLoop::processEvents (this=<value optimized out>, flags=) at kernel/qeventloop.cpp:149
#38 0x00007ffbe206fd9c in QEventLoop::exec (this=0x7fff36126e60, flags=) at kernel/qeventloop.cpp:201
#39 0x00007ffbe2074a2b in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1003
#40 0x0000000000403462 in main (argc=<value optimized out>, argv=<value optimized out>) at ../../kmail/main.cpp:156

Reported using DrKonqi