Version:           1.11.0 (using KDE 4.2.0)
Installed from:    Ubuntu Packages

When firing up kmail, the first thing I do is cleaning up my inbox. I just display mail with status "new", and do the following:

(1) Select a bunch of mail I can see in the contact list, and hit delete.
(2) While deleting is in progress I select some other mail and hit delete again.
(3) Goto (1)

This procedure terminates after one at most three iterations. The computed function is a crash report with this backtrace:

Application: KMail (kmail), signal SIGSEGV

Thread 1 (Thread 0xb40206c0 (LWP 31558)):
[KCrash Handler]
#6  KMail::FolderJob::msgList (this=0x3690036) at /usr/include/qt4/QtCore/qlist.h:107
#7  0xb75958ab in KMAcctImap::ignoreJobsForMessage (this=0x82c5060, msg=0x8f594a8) at /build/buildd/kdepim-4.2.0/kmail/kmacctimap.cpp:215
#8  0xb75ae375 in KMFolderImap::ignoreJobsForMessage (this=0x831d0e8, msg=0x8f594a8) at /build/buildd/kdepim-4.2.0/kmail/kmfolderimap.cpp:1562
#9  0xb76cef6e in KMMoveCommand::execute (this=0x8f69e70) at /build/buildd/kdepim-4.2.0/kmail/kmcommands.cpp:2086
#10 0xb76b2222 in KMCommand::slotPostTransfer (this=0x8f69e70, result=KMCommand::OK) at /build/buildd/kdepim-4.2.0/kmail/kmcommands.cpp:276
#11 0xb76bdb54 in KMCommand::qt_metacall (this=0x8f69e70, _c=QMetaObject::InvokeMetaMethod, _id=5, _a=0xbfacc19c) at /build/buildd/kdepim-4.2.0/obj-i486-linux-gnu/kmail/kmcommands.moc:86
#12 0xb76d0e3a in KMMoveCommand::qt_metacall (this=0x8f69e70, _c=QMetaObject::InvokeMetaMethod, _id=9, _a=0xbfacc19c) at /build/buildd/kdepim-4.2.0/obj-i486-linux-gnu/kmail/kmcommands.moc:1662
#13 0xb76d0f02 in KMDeleteMsgCommand::qt_metacall (this=0x8f69e70, _c=QMetaObject::InvokeMetaMethod, _id=9, _a=0xbfacc19c) at /build/buildd/kdepim-4.2.0/obj-i486-linux-gnu/kmail/kmcommands.moc:1712
#14 0xb616aa60 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#15 0xb616b7e2 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#16 0xb76ae8d3 in KMCommand::messagesTransfered (this=0x8f69e70, _t1=KMCommand::OK) at /build/buildd/kdepim-4.2.0/obj-i486-linux-gnu/kmail/kmcommands.moc:100
#17 0xb76cd79c in KMCommand::transferSelectedMsgs (this=0x8f69e70) at /build/buildd/kdepim-4.2.0/kmail/kmcommands.cpp:370
#18 0xb76cd9ef in KMCommand::slotStart (this=0x8f69e70) at /build/buildd/kdepim-4.2.0/kmail/kmcommands.cpp:268
#19 0xb76bdb63 in KMCommand::qt_metacall (this=0x8f69e70, _c=QMetaObject::InvokeMetaMethod, _id=4, _a=0xbfacc398) at /build/buildd/kdepim-4.2.0/obj-i486-linux-gnu/kmail/kmcommands.moc:85
#20 0xb76d0e3a in KMMoveCommand::qt_metacall (this=0x8f69e70, _c=QMetaObject::InvokeMetaMethod, _id=8, _a=0xbfacc398) at /build/buildd/kdepim-4.2.0/obj-i486-linux-gnu/kmail/kmcommands.moc:1662
#21 0xb76d0f02 in KMDeleteMsgCommand::qt_metacall (this=0x8f69e70, _c=QMetaObject::InvokeMetaMethod, _id=8, _a=0xbfacc398) at /build/buildd/kdepim-4.2.0/obj-i486-linux-gnu/kmail/kmcommands.moc:1712
#22 0xb616aa60 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#23 0xb616b7e2 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#24 0xb6170db7 in ?? () from /usr/lib/libQtCore.so.4
#25 0xb6170edc in ?? () from /usr/lib/libQtCore.so.4
#26 0xb616553f in QObject::event () from /usr/lib/libQtCore.so.4
#27 0xb63e58ec in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#28 0xb63ed72e in QApplication::notify () from /usr/lib/libQtGui.so.4
#29 0xb7ee5fed in KApplication::notify (this=0xbfaccb48, receiver=0x8f569c0, event=0xbfacc82c) at /build/buildd/kde4libs-4.2.0/kdeui/kernel/kapplication.cpp:307
#30 0xb6155e61 in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#31 0xb6183d81 in ?? () from /usr/lib/libQtCore.so.4
#32 0xb6180520 in ?? () from /usr/lib/libQtCore.so.4
#33 0xb479f6f8 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#34 0xb47a2da3 in ?? () from /usr/lib/libglib-2.0.so.0
#35 0xb47a2f61 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#36 0xb6180478 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#37 0xb647fea5 in ?? () from /usr/lib/libQtGui.so.4
#38 0xb615452a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#39 0xb61546ea in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#40 0xb6156da5 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#41 0xb63e5767 in QApplication::exec () from /usr/lib/libQtGui.so.4
#42 0x0804a7a0 in main (argc=) at /build/buildd/kdepim-4.2.0/kmail/main.cpp:146


I can observe this behavior since using kmail for kde 4. Always using packages from ubuntu's ppa repository.