Version:           1.8 (using KDE 3.4.0, Debian Package 4:3.4.0-0ubuntu3 (3.1))
Compiler:          gcc version 3.3.5 (Debian 1:3.3.5-8ubuntu2)
OS:                Linux (x86_64) release 2.6.11

When filtering through the emails in a folder (both when filtering an individual message, and a selection of messages), kmail crashes on some of my emails. On restarting kmail, the message has become duplicated (but only one physical file representing the email in ~/Mail/blah).

Unfortunately, I could not consistently get kmail to crash on the same email (although as far as I can remember, the crash seemed to be happening with emails from the same guy). Also, I seem to be loosing emails (what seems to be happening is that the message that is to be filtered becomes duplicated, so I restart kmail, and remove the duplicate message. Then, the other message disappears as well (kmail reports subject as "no subject", sender and date as "unknown", and a blank email body.).)

If any kmail devs can tell me how to properly back up my mails to guarantee that I don't lose emails, then I'll be happy to investigate the bug further. But otherwise, I've already lost a few hundred emails to this bug after filtering a folder, crashing removing the duplicated messages and then discovering that the emails were gone). So this bug is definitely critical.

The crash occurs with both the kmail packages provided in kubuntu, as well as compiled with debugging options (from kubuntu sources). While investigating, I managed to get 3 slightly different crash stacks:

[KCrash handler]
#3  0x00002aaaaaef78d6 in KMail::SortCacheItem::addSortedChild (
    this=0x14545a0, i=0x70) at headeritem.h:87
#4  0x00002aaaaaeec588 in KMHeaders::msgAdded (this=0xa9a530, id=513)
    at kmheaders.cpp:917
#5  0x00002aaaaaef5a4d in KMHeaders::qt_invoke (this=0xa9a530, _id=111, 
    _o=0x7fffffffe3e0) at kmheaders.moc:298
#6  0x00002aaaaf725b03 in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#7  0x00002aaaaf725ca2 in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#8  0x00002aaaaaf276b5 in KMFolder::msgAdded (this=0x9d7360, t0=513)
    at kmfolder.moc:266
#9  0x00002aaaaaf27f12 in KMFolder::qt_emit (this=0x9d7360, _id=11, 
    _o=0x7fffffffe510) at kmfolder.moc:369
#10 0x00002aaaaf725bb4 in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#11 0x00002aaaaf725ca2 in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#12 0x00002aaaaaf3f46f in FolderStorage::msgAdded (this=0x9d7510, t0=513)
    at folderstorage.moc:300
#13 0x00002aaaaaf3bf08 in FolderStorage::emitMsgAddedSignals (this=0x9d7510, 
    idx=513) at folderstorage.cpp:253
#14 0x00002aaaaafc2e1d in KMFolderMaildir::addMsgInternal (this=0x9d7510, 
    aMsg=0xa559a0, index_return=0x0, stripUid=false)
    at kmfoldermaildir.cpp:528
#15 0x00002aaaaafc22cb in KMFolderMaildir::addMsg (this=0x9d7510, 
    aMsg=0xa559a0, index_return=0x0) at kmfoldermaildir.cpp:366
#16 0x00002aaaaaf40712 in FolderStorage::addMsgKeepUID (this=0x9d7510, 
    msg=0xa559a0, index_return=0x0) at folderstorage.h:204
#17 0x00002aaaaaf25870 in KMFolder::addMsgKeepUID (this=0x9d7360, 
    msg=0xa559a0, index_return=0x0) at kmfolder.cpp:334
#18 0x00002aaaaaf684c1 in KMFilterMgr::endFiltering (this=0x9816e0, 
    msgBase=0xa559a0) at kmfiltermgr.cpp:169
#19 0x00002aaaaaf6892c in KMFilterMgr::process (this=0x9816e0, msg=0xa559a0, 
    set=Explicit) at kmfiltermgr.cpp:255
#20 0x00002aaaaaeed563 in KMHeaders::slotFilterMsg (this=0xa9a530, 
    msg=0xa559a0) at kmheaders.cpp:1169
#21 0x00002aaaaaeedd4a in KMHeaders::applyFiltersOnMsg (this=0xa9a530)
    at kmheaders.cpp:1310
#22 0x00002aaaab03ca6d in KMMainWidget::slotApplyFilters (this=0xa74310)
    at kmmainwidget.cpp:1484



[KCrash handler]
#3  0x00002aaaaf7e1b51 in QListViewItem::QListViewItem ()
   from /usr/lib/libqt-mt.so.3
#4  0x00002aaaae486439 in KListViewItem::KListViewItem ()
   from /usr/lib/libkdeui.so.4
#5  0x00002aaaaaef88f0 in HeaderItem (this=0xcf9db0, parent=0x2aaaacd28a50, 
    msgId=542, key=@0x2aaaafcf0b48) at headeritem.cpp:60
#6  0x00002aaaaaeebfa4 in KMHeaders::msgAdded (this=0xa8ccc0, id=542)
    at kmheaders.cpp:833
#7  0x00002aaaaaef5a4d in KMHeaders::qt_invoke (this=0xa8ccc0, _id=111, 
    _o=0x7fffffffe3e0) at kmheaders.moc:298
#8  0x00002aaaaf725b03 in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#9  0x00002aaaaf725ca2 in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#10 0x00002aaaaaf276b5 in KMFolder::msgAdded (this=0x9cfa70, t0=542)
    at kmfolder.moc:266
#11 0x00002aaaaaf27f12 in KMFolder::qt_emit (this=0x9cfa70, _id=11, 
    _o=0x7fffffffe510) at kmfolder.moc:369
#12 0x00002aaaaf725bb4 in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#13 0x00002aaaaf725ca2 in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#14 0x00002aaaaaf3f46f in FolderStorage::msgAdded (this=0x9cfc20, t0=542)
    at folderstorage.moc:300
#15 0x00002aaaaaf3bf08 in FolderStorage::emitMsgAddedSignals (this=0x9cfc20, 
    idx=542) at folderstorage.cpp:253
#16 0x00002aaaaafc2e1d in KMFolderMaildir::addMsgInternal (this=0x9cfc20, 
    aMsg=0xf7b100, index_return=0x0, stripUid=false)
    at kmfoldermaildir.cpp:528
#17 0x00002aaaaafc22cb in KMFolderMaildir::addMsg (this=0x9cfc20, 
    aMsg=0xf7b100, index_return=0x0) at kmfoldermaildir.cpp:366
#18 0x00002aaaaaf40712 in FolderStorage::addMsgKeepUID (this=0x9cfc20, 
    msg=0xf7b100, index_return=0x0) at folderstorage.h:204
#19 0x00002aaaaaf25870 in KMFolder::addMsgKeepUID (this=0x9cfa70, 
    msg=0xf7b100, index_return=0x0) at kmfolder.cpp:334
#20 0x00002aaaaaf684c1 in KMFilterMgr::endFiltering (this=0x9847b0, 
    msgBase=0xf7b100) at kmfiltermgr.cpp:169
#21 0x00002aaaaaf6892c in KMFilterMgr::process (this=0x9847b0, msg=0xf7b100, 
    set=Explicit) at kmfiltermgr.cpp:255
#22 0x00002aaaaaeed563 in KMHeaders::slotFilterMsg (this=0xa8ccc0, 
    msg=0xf7b100) at kmheaders.cpp:1169
#23 0x00002aaaaaeedd4a in KMHeaders::applyFiltersOnMsg (this=0xa8ccc0)
    at kmheaders.cpp:1310
#24 0x00002aaaab03ca6d in KMMainWidget::slotApplyFilters (this=0xa674d0)
    at kmmainwidget.cpp:1484




[KCrash handler]
#3  0x00002aaaaaeeceaa in KMHeaders::msgRemoved (this=0xa8c8b0, id=523, msgId=
      {static null = {static null = <same as static member of an already seen type>, d = 0x508da0, static shared_null = 0x508da0}, d = 0xfac000, static shared_null = 0x508da0}) at kmheaders.cpp:1049
#4  0x00002aaaaaef5a98 in KMHeaders::qt_invoke (this=0xa8c8b0, _id=112, 
    _o=0x7fffffffe4e0) at kmheaders.moc:299
#5  0x00002aaaaf725b83 in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#6  0x00002aaaaaf27561 in KMFolder::msgRemoved (this=0x9cf470, t0=523, t1=
      {static null = {static null = <same as static member of an already seen type>, d = 0x508da0, static shared_null = 0x508da0}, d = 0xfac000, static shared_null = 0x508da0}) at kmfolder.moc:247
#7  0x00002aaaaaf27ec0 in KMFolder::qt_emit (this=0x9cf470, _id=9, 
    _o=0x7fffffffe650) at kmfolder.moc:367
#8  0x00002aaaaf725bb4 in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#9  0x00002aaaaaf3f31b in FolderStorage::msgRemoved (this=0x9cf620, t0=523, 
    t1=
      {static null = {static null = <same as static member of an already seen type>, d = 0x508da0, static shared_null = 0x508da0}, d = 0xfac000, static shared_null = 0x508da0}) at folderstorage.moc:281
#10 0x00002aaaaaf3c6f2 in FolderStorage::take (this=0x9cf620, idx=523)
    at folderstorage.cpp:398
#11 0x00002aaaaafc4c6c in KMFolderMaildir::take (this=0x9cf620, idx=523)
    at kmfoldermaildir.cpp:927
#12 0x00002aaaaaf257ab in KMFolder::take (this=0x9cf470, idx=523)
    at kmfolder.cpp:319
#13 0x00002aaaaaf684af in KMFilterMgr::endFiltering (this=0x978be0, 
    msgBase=0xcfddf0) at kmfiltermgr.cpp:168
#14 0x00002aaaaaf6892c in KMFilterMgr::process (this=0x978be0, msg=0xcfddf0, 
    set=Explicit) at kmfiltermgr.cpp:255
#15 0x00002aaaaaeed563 in KMHeaders::slotFilterMsg (this=0xa8c8b0, 
    msg=0xcfddf0) at kmheaders.cpp:1169
#16 0x00002aaaaaeedd4a in KMHeaders::applyFiltersOnMsg (this=0xa8c8b0)
    at kmheaders.cpp:1310
#17 0x00002aaaab03ca6d in KMMainWidget::slotApplyFilters (this=0xa66fd0)
    at kmmainwidget.cpp:1484