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-gentoo-r1-Dom0 x86_64

What I was doing when the application crashed:
I use Kontact and KMail with 9 IMAP Accounts, more than 100 folders, subfolders and much more mails. I have this crash more than one time a hour in KDE4 (from KDE 4.2, my first KDE4 version). With KDE3 it was not a problem. The whole KDE4 configuration is new. I doesn't migrate config files. My other system (same hardware), same Gentoo Patch level, same Flags word perfect with 3 IMAP accounts. 

The IMAP server is a dovecot system at my provider and one account is at web.de. 

I hope this report is helpfull.

 -- Backtrace:
Application: KMail (kmail), signal: Segmentation fault
[KCrash Handler]
#5  QAbstractSocketEngine::state (this=0x2000000a68190) at socket/qabstractsocketengine.cpp:184
#6  0x00007f8e4e009090 in QNativeSocketEngine::waitForReadOrWrite (this=0x2000000a68190, readyToRead=0x7fffe61fac3f, readyToWrite=0x7fffe61fac3e, checkRead=<value optimized out>, 
    checkWrite=<value optimized out>, msecs=-1, timedOut=0x0) at socket/qnativesocketengine.cpp:921
#7  0x00007f8e4e017495 in QAbstractSocket::waitForBytesWritten (this=0x162a830, msecs=-1) at socket/qabstractsocket.cpp:1758
#8  0x00007f8e4ee02c5a in KIO::SocketConnectionBackend::sendCommand (this=0x172ab00, task=...) at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4/kio/kio/connection.cpp:294
#9  0x00007f8e4ee02970 in KIO::Connection::sendnow (this=0x8da700, _cmd=85, data=...) at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4/kio/kio/connection.cpp:502
#10 0x00007f8e4ee03ade in KIO::ConnectionPrivate::dequeue (this=0x1798b70) at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4/kio/kio/connection.cpp:78
#11 0x00007f8e4eee4194 in KIO::Slave::accept (this=0x173bce0) at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4/kio/kio/slave.cpp:118
#12 0x00007f8e4eee6a80 in KIO::Slave::qt_metacall (this=0x173bce0, _c=QMetaObject::InvokeMetaMethod, _id=532, _a=0x7fffe61fae10)
    at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4_build/kio/slave.moc:75
#13 0x00007f8e4e5d848e in QMetaObject::activate (sender=0x8e2500, from_signal_index=<value optimized out>, to_signal_index=4, argv=0x31) at kernel/qobject.cpp:3101
#14 0x00007f8e4ee02295 in KIO::ConnectionServer::qt_metacall (this=0x8e2500, _c=QMetaObject::InvokeMetaMethod, _id=532, _a=<value optimized out>)
    at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4_build/kio/connection.moc:134
#15 0x00007f8e4e5d848e in QMetaObject::activate (sender=0x1b05fd0, from_signal_index=<value optimized out>, to_signal_index=6, argv=0x31) at kernel/qobject.cpp:3101
#16 0x00007f8e4ee02320 in KIO::AbstractConnectionBackend::qt_metacall (this=0x1b05fd0, _c=QMetaObject::InvokeMetaMethod, _id=532, _a=0x7fffe61fb040)
    at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4_build/kio/connection_p.moc:72
#17 0x00007f8e4ee0318d in KIO::SocketConnectionBackend::qt_metacall (this=0x2000000a68190, _c=3860835391, _id=-434131906, _a=0x31)
    at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4_build/kio/connection_p.moc:141
#18 0x00007f8e4e5d848e in QMetaObject::activate (sender=0x16e29f0, from_signal_index=<value optimized out>, to_signal_index=4, argv=0x31) at kernel/qobject.cpp:3101
#19 0x00007f8e52aa9a83 in KLocalSocketServer::incomingConnection (this=0x16e29f0, descriptor=2417) at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4/kdecore/network/klocalsocket.cpp:212
#20 0x00007f8e52b3d7f1 in KLocalSocketServerPrivate::processSocketActivity (this=0x16afba0) at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4/kdecore/network/klocalsocket_unix.cpp:394
#21 0x00007f8e52aa944c in KLocalSocketServer::qt_metacall (this=0x16e29f0, _c=QMetaObject::InvokeMetaMethod, _id=532, _a=<value optimized out>)
    at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4_build/kdecore/klocalsocket.moc:128
#22 0x00007f8e4e5d848e in QMetaObject::activate (sender=0xb54e60, from_signal_index=<value optimized out>, to_signal_index=4, argv=0x31) at kernel/qobject.cpp:3101
#23 0x00007f8e4e6098ee in QSocketNotifier::activated (this=0x2000000a68190, _t1=2416) at .moc/release-shared/moc_qsocketnotifier.cpp:83
#24 0x00007f8e4e5de183 in QSocketNotifier::event (this=0xb54e60, e=0x7fffe61fb800) at kernel/qsocketnotifier.cpp:316
#25 0x00007f8e4d441b8d in QApplicationPrivate::notify_helper (this=0x636370, receiver=0xb54e60, e=0x7fffe61fb800) at kernel/qapplication.cpp:4065
#26 0x00007f8e4d44931a in QApplication::notify (this=0x7fffe61fbc10, receiver=0xb54e60, e=0x7fffe61fb800) at kernel/qapplication.cpp:4030
#27 0x00007f8e52fd392b in KApplication::notify (this=0x7fffe61fbc10, receiver=0xb54e60, event=0x7fffe61fb800)
    at /var/tmp/portage/kde-base/kdelibs-4.3.4/work/kdelibs-4.3.4/kdeui/kernel/kapplication.cpp:302
#28 0x00007f8e4e5c6993 in QCoreApplication::notifyInternal (this=0x7fffe61fbc10, receiver=0xb54e60, event=0x7fffe61fb800) at kernel/qcoreapplication.cpp:606
#29 0x00007f8e4e5eafd9 in QCoreApplication::sendEvent (source=0x638d90) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#30 socketNotifierSourceDispatch (source=0x638d90) at kernel/qeventdispatcher_glib.cpp:110
#31 0x00007f8e45eb1e51 in g_main_dispatch (context=0x638c40) at gmain.c:1824
#32 IA__g_main_context_dispatch (context=0x638c40) at gmain.c:2377
#33 0x00007f8e45eb53e8 in g_main_context_iterate (context=0x638c40, block=1, dispatch=1, self=<value optimized out>) at gmain.c:2455
#34 0x00007f8e45eb559c in IA__g_main_context_iteration (context=0x638c40, may_block=1) at gmain.c:2518
#35 0x00007f8e4e5ead6f in QEventDispatcherGlib::processEvents (this=0x63d890, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#36 0x00007f8e4d4c5caf in QGuiEventDispatcherGlib::processEvents (this=0x2000000a68190, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#37 0x00007f8e4e5c53c2 in QEventLoop::processEvents (this=<value optimized out>, flags=...) at kernel/qeventloop.cpp:149
#38 0x00007f8e4e5c555c in QEventLoop::exec (this=0x7fffe61fba60, flags=...) at kernel/qeventloop.cpp:197
#39 0x00007f8e4e5c74f4 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#40 0x000000000040336b in _start ()

Reported using DrKonqi