I just updated my build this morning (rev: 825458), kmail now crashes every 
time I click on 'send queued mail'. Backtrace:


Application: KMail (kmail), signal SIGABRT
Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread -1209231664 (LWP 29188)]
[New Thread -1271059568 (LWP 29294)]
[KCrash handler]
#6  0x00110402 in __kernel_vsyscall ()
#7  0x014d9690 in raise () from /lib/libc.so.6
#8  0x014daf91 in abort () from /lib/libc.so.6
#9  0x0015bbc9 in qt_message_output (msgType=QtFatalMsg, 
    buf=0xbff1a2c0 "ASSERT: \"false\" in file 
/home/kde-devel/kde/src/kdepimlibs/mailtransport/transportmanager.cpp, line 
233") at global/qglobal.cpp:2058
#10 0x0015bc2d in qFatal (msg=0x2ac518 "ASSERT: \"%s\" in file %s, line %d")
    at global/qglobal.cpp:2260
#11 0x0015c093 in qt_assert (assertion=0x7be524 "false", 
    file=0x7be3e8 
"/home/kde-devel/kde/src/kdepimlibs/mailtransport/transportmanager.cpp", 
line=233) at global/qglobal.cpp:1828
#12 0x007a9191 in MailTransport::TransportManager::createTransportJob (
    this=0x91bea70, transport=@0xbff1c400)
    at /home/kde-devel/kde/src/kdepimlibs/mailtransport/transportmanager.cpp:233
#13 0x00caca1d in KMSender::doSendMsg (this=0x9283f98)
    at /home/kde-devel/kde/src/kdepim/kmail/kmsender.cpp:535
#14 0x00cade70 in KMSender::doSendQueued (this=0x9283f98, 
    customTransport=@0xbff1c5cc)
    at /home/kde-devel/kde/src/kdepim/kmail/kmsender.cpp:251
#15 0x00cae60f in KMail::MessageSender::sendQueued (this=0x9283fa0, 
    transport=@0xbff1c5cc)
    at /home/kde-devel/kde/src/kdepim/kmail/messagesender.h:77
#16 0x00e31f43 in KMMainWidget::slotSendQueued (this=0x933efc0)
    at /home/kde-devel/kde/src/kdepim/kmail/kmmainwidget.cpp:2016
#17 0x00e535d3 in KMMainWidget::qt_metacall (this=0x933efc0, 
    _c=QMetaObject::InvokeMetaMethod, _id=98, _a=0xbff1c70c)
    at /home/kde-devel/kde/build/kdepim/kmail/kmmainwidget.moc:417
#18 0x0026ae61 in QMetaObject::activate (sender=0x96577e0, 
    from_signal_index=5, to_signal_index=6, argv=0xbff1c70c)
    at kernel/qobject.cpp:3007
#19 0x0026b06a in QMetaObject::activate (sender=0x96577e0, m=0x36ffe60, 
    from_local_signal_index=1, to_local_signal_index=2, argv=0xbff1c70c)
    at kernel/qobject.cpp:3100
#20 0x02ff3dca in QAction::triggered (this=0x96577e0, _t1=false)
    at .moc/debug-shared/moc_qaction.cpp:216
#21 0x02ff5cde in QAction::activate (this=0x96577e0, event=QAction::Trigger)
    at kernel/qaction.cpp:1119
#22 0x03422c4c in QMenuPrivate::activateAction (this=0x9b639f8, 
    action=0x96577e0, action_e=QAction::Trigger, self=true)
    at widgets/qmenu.cpp:1005
#23 0x03425659 in QMenu::mouseReleaseEvent (this=0x9a91140, e=0xbff1cff4)
    at widgets/qmenu.cpp:2160
#24 0x0464e026 in KMenu::mouseReleaseEvent (this=0x9a91140, e=0xbff1cff4)
    at /home/kde-devel/kde/src/kdelibs/kdeui/widgets/kmenu.cpp:452
#25 0x0305ba43 in QWidget::event (this=0x9a91140, event=0xbff1cff4)
    at kernel/qwidget.cpp:6927
#26 0x03420862 in QMenu::event (this=0x9a91140, e=0xbff1cff4)
    at widgets/qmenu.cpp:2256
#27 0x02ffbd07 in QApplicationPrivate::notify_helper (this=0x9064948, 
    receiver=0x9a91140, e=0xbff1cff4) at kernel/qapplication.cpp:3772
#28 0x02ffc88c in QApplication::notify (this=0xbff1eb9c, receiver=0x9a91140, 
    e=0xbff1cff4) at kernel/qapplication.cpp:3501
#29 0x04584267 in KApplication::notify (this=0xbff1eb9c, receiver=0x9a91140, 
    event=0xbff1cff4)
    at /home/kde-devel/kde/src/kdelibs/kdeui/kernel/kapplication.cpp:311
#30 0x00256bb2 in QCoreApplication::notifyInternal (this=0xbff1eb9c, 
    receiver=0x9a91140, event=0xbff1cff4) at kernel/qcoreapplication.cpp:583
#31 0x03008165 in QCoreApplication::sendSpontaneousEvent (receiver=0x9a91140, 
    event=0xbff1cff4)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218
#32 0x03002cb6 in QApplicationPrivate::sendMouseEvent (receiver=0x9a91140, 
    event=0xbff1cff4, alienWidget=0x0, nativeWidget=0x9a91140, 
    buttonDown=0x371e280, lastMouseReceiver=@0x371e284)
    at kernel/qapplication.cpp:2766
#33 0x03077817 in QETWidget::translateMouseEvent (this=0x9a91140, 
    event=0xbff1d5d0) at kernel/qapplication_x11.cpp:4067
#34 0x03075512 in QApplication::x11ProcessEvent (this=0xbff1eb9c, 
    event=0xbff1d5d0) at kernel/qapplication_x11.cpp:3133
#35 0x030a4560 in x11EventSourceDispatch (s=0x90676b0, callback=0, 
    user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:148
#36 0x073421ac in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#37 0x073455ef in ?? () from /lib/libglib-2.0.so.0
#38 0x07345b55 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#39 0x00285be4 in QEventDispatcherGlib::processEvents (this=0x9061550, 
    flags=@0xbff1d778) at kernel/qeventdispatcher_glib.cpp:325
#40 0x030a3db4 in QGuiEventDispatcherGlib::processEvents (this=0x9061550, 
    flags=@0xbff1d7a8) at kernel/qguieventdispatcher_glib.cpp:204
#41 0x0025370e in QEventLoop::processEvents (this=0xbff1d824, 
    flags=@0xbff1d7e4) at kernel/qeventloop.cpp:149
#42 0x0025394d in QEventLoop::exec (this=0xbff1d824, flags=@0xbff1d82c)
    at kernel/qeventloop.cpp:196
#43 0x03425968 in QMenu::exec (this=0x9a91140, p=@0xbff1db6c, action=0x0)
    at widgets/qmenu.cpp:1929
#44 0x00bded85 in KMFolderTree::slotContextMenuRequested (this=0x95bf520, 
    lvi=0x9691f78, p=@0xbff1db6c)
    at /home/kde-devel/kde/src/kdepim/kmail/kmfoldertree.cpp:1176
#45 0x00bdfec8 in KMFolderTree::qt_metacall (this=0x95bf520, 
    _c=QMetaObject::InvokeMetaMethod, _id=40, _a=0xbff1dac4)
    at /home/kde-devel/kde/build/kdepim/kmail/kmfoldertree.moc:278
#46 0x0026ae61 in QMetaObject::activate (sender=0x95bf520, 
    from_signal_index=65, to_signal_index=65, argv=0xbff1dac4)
    at kernel/qobject.cpp:3007
#47 0x0026b2e3 in QMetaObject::activate (sender=0x95bf520, m=0x3e25e68, 
    local_signal_index=15, argv=0xbff1dac4) at kernel/qobject.cpp:3080
#48 0x03df90e4 in Q3ListView::contextMenuRequested (this=0x95bf520, 
    _t1=0x9691f78, _t2=@0xbff1db6c, _t3=0)
    at .moc/debug-shared/moc_q3listview.cpp:370
#49 0x03c9134e in Q3ListView::contentsContextMenuEvent (this=0x95bf520, 
    e=0xbff1dbdc) at itemviews/q3listview.cpp:4360
#50 0x07e8c88c in K3ListView::contentsContextMenuEvent (this=0x95bf520, 
    event=0xbff1dbdc)
    at /home/kde-devel/kde/src/kdelibs/kde3support/kdeui/k3listview.cpp:1283
#51 0x03cfe43c in Q3ScrollView::viewportContextMenuEvent (this=0x95bf520, 
    e=0xbff1e274) at widgets/q3scrollview.cpp:1897
#52 0x03cffa06 in Q3ScrollView::eventFilter (this=0x95bf520, obj=0x95c11e0, 
    e=0xbff1e274) at widgets/q3scrollview.cpp:1541
#53 0x03c92a74 in Q3ListView::eventFilter (this=0x95bf520, o=0x95c11e0, 
    e=0xbff1e274) at itemviews/q3listview.cpp:3777
#54 0x00bd6205 in KMFolderTree::eventFilter (this=0x95bf520, o=0x95c11e0, 
    e=0xbff1e274)
    at /home/kde-devel/kde/src/kdepim/kmail/kmfoldertree.cpp:1811
#55 0x00254e42 in QCoreApplicationPrivate::sendThroughObjectEventFilters (
    this=0x9064948, receiver=0x95c11e0, event=0xbff1e274)
    at kernel/qcoreapplication.cpp:694
#56 0x02ffbce1 in QApplicationPrivate::notify_helper (this=0x9064948, 
    receiver=0x95c11e0, e=0xbff1e274) at kernel/qapplication.cpp:3768
#57 0x02ffd076 in QApplication::notify (this=0xbff1eb9c, receiver=0x95c11e0, 
    e=0xbff1e274) at kernel/qapplication.cpp:3586
#58 0x04584267 in KApplication::notify (this=0xbff1eb9c, receiver=0x95c11e0, 
    event=0xbff1e274)
    at /home/kde-devel/kde/src/kdelibs/kdeui/kernel/kapplication.cpp:311
#59 0x00256bb2 in QCoreApplication::notifyInternal (this=0xbff1eb9c, 
    receiver=0x95c11e0, event=0xbff1e274) at kernel/qcoreapplication.cpp:583
#60 0x03008165 in QCoreApplication::sendSpontaneousEvent (receiver=0x95c11e0, 
    event=0xbff1e274)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218
#61 0x03077b30 in QETWidget::translateMouseEvent (this=0x933efc0, 
    event=0xbff1e850) at kernel/qapplication_x11.cpp:4139
#62 0x03075512 in QApplication::x11ProcessEvent (this=0xbff1eb9c, 
    event=0xbff1e850) at kernel/qapplication_x11.cpp:3133
#63 0x030a4560 in x11EventSourceDispatch (s=0x90676b0, callback=0, 
    user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:148
#64 0x073421ac in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#65 0x073455ef in ?? () from /lib/libglib-2.0.so.0
#66 0x07345b55 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#67 0x00285be4 in QEventDispatcherGlib::processEvents (this=0x9061550, 
    flags=@0xbff1e9f8) at kernel/qeventdispatcher_glib.cpp:325
#68 0x030a3db4 in QGuiEventDispatcherGlib::processEvents (this=0x9061550, 
    flags=@0xbff1ea28) at kernel/qguieventdispatcher_glib.cpp:204
#69 0x0025370e in QEventLoop::processEvents (this=0xbff1eaa0, 
    flags=@0xbff1ea64) at kernel/qeventloop.cpp:149
#70 0x0025394d in QEventLoop::exec (this=0xbff1eaa0, flags=@0xbff1eaa8)
    at kernel/qeventloop.cpp:196
#71 0x0025739b in QCoreApplication::exec () at kernel/qcoreapplication.cpp:845
#72 0x02ffba04 in QApplication::exec () at kernel/qapplication.cpp:3304
#73 0x0804aff0 in main (argc=3, argv=0xbff1ec74)
    at /home/kde-devel/kde/src/kdepim/kmail/main.cpp:130
#0  0x00110402 in __kernel_vsyscall ()