Version:           1.9.50 (using 4.00.60 (KDE 4.0.60 >= 20080129), Gentoo)
Compiler:          i686-pc-linux-gnu-gcc
OS:                Linux (i686) release 2.6.23-gentoo-r3

Steps to reproduce:

1) Set your account preferences so that you drafts folder is on an IMAP account
2) Create a new mail
3) Save that mail to Drafts folder
4) You are asked for your username / password for the IMAP folder
5) Just click "ok" without providing password
6) See kmail crash with the following backtrace:
  
Application: KMail (kmail), signal SIGABRT 
Using host libthread_db library "/lib/libthread_db.so.1". 
[Thread debugging using libthread_db enabled] 
[New Thread 0xb4b366d0 (LWP 21846)] 
[KCrash handler] 
#6  0xffffe410 in __kernel_vsyscall () 
#7  0xb50f61f1 in *__GI_raise (sig=6) 
    at ../nptl/sysdeps/unix/sysv/linux/raise.c:64 
#8  0xb50f79b8 in *__GI_abort () at abort.c:88 
#9  0xb7e3b265 in qt_message_output (msgType=QtFatalMsg, 
    buf=0xbfd9f8cc "ASSERT: \"!mSlave\" in file /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/imapaccountbase.cpp, line 299") 
    at global/qglobal.cpp:2160 
#10 0xb7e3b32a in qFatal (msg=0xb7f4287c "ASSERT: \"%s\" in file %s, line %d") 
    at global/qglobal.cpp:2392 
#11 0xb7e3b555 in qt_assert (assertion=0xb79d0072 "!mSlave", 
    file=0xb79cf5c8 "/var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/imapaccountbase.cpp", line=299) at global/qglobal.cpp:1917 
#12 0xb77ba9c8 in KMail::ImapAccountBase::makeConnection (this=0x81fc9d0) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/imapaccountbase.cpp:299 
#13 0xb77c1508 in KMAcctImap::makeConnection (this=0x6) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/kmacctimap.cpp:546 
#14 0xb77d6265 in KMFolderImap::checkValidity (this=0x8211608) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/kmfolderimap.cpp:1068 
#15 0xb77d6a42 in KMFolderImap::getFolder (this=0x8211608, force=false) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/kmfolderimap.cpp:1259 
#16 0xb770f3c4 in KMComposeWin::saveDraftOrTemplate (this=0x820b6c8, 
    folderName=@0xbfda1da0, msg=<value optimized out>) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/kmcomposewin.cpp:3674 
#17 0xb77173c4 in KMComposeWin::slotContinueDoSend (this=0x820b6c8, 
    sentOk=false) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/kmcomposewin.cpp:3701 
#18 0xb77287e4 in KMComposeWin::qt_metacall (this=0x820b6c8, 
    _c=QMetaObject::InvokeMetaMethod, _id=148, _a=0xbfda22fc) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim_build/kmail/kmcomposewin.moc:355 
#19 0xb7f211f4 in QMetaObject::activate (sender=0x820b6c8, 
    from_signal_index=47, to_signal_index=47, argv=<value optimized out>) 
    at kernel/qobject.cpp:3081 
#20 0xb7f21d94 in QMetaObject::activate (sender=0x820b6c8, m=0xb7a1944c, 
    local_signal_index=0, argv=0xbfda22fc) at kernel/qobject.cpp:3140 
#21 0xb7725d67 in KMComposeWin::applyChangesDone (this=0x820b6c8, _t1=true) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim_build/kmail/kmcomposewin.moc:371 
#22 0xb7725dc8 in KMComposeWin::slotComposerDone (this=0x820b6c8, rc=true) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/kmcomposewin.cpp:2087 
#23 0xb77287ca in KMComposeWin::qt_metacall (this=0x820b6c8, 
    _c=QMetaObject::InvokeMetaMethod, _id=147, _a=0xbfda283c) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim_build/kmail/kmcomposewin.moc:354 
#24 0xb7f211f4 in QMetaObject::activate (sender=0x836c3d8, 
    from_signal_index=4, to_signal_index=4, argv=<value optimized out>) 
    at kernel/qobject.cpp:3081 
#25 0xb7f21d94 in QMetaObject::activate (sender=0x836c3d8, m=0xb7a24224, 
    local_signal_index=0, argv=0xbfda283c) at kernel/qobject.cpp:3140 
#26 0xb78f4a47 in MessageComposer::done (this=0x836c3d8, _t1=true) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim_build/kmail/messagecomposer.moc:79 
#27 0xb78ff247 in MessageComposer::emitDone (this=0x836c3d8, ok=true) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/messagecomposer.cpp:410 
#28 0xb78ff2af in MessageComposer::doNextJob (this=0x836c3d8) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/messagecomposer.cpp:386 
#29 0xb78ff438 in MessageComposer::slotDoNextJob (this=0x836c3d8) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/messagecomposer.cpp:433 
#30 0xb78ff4c9 in MessageComposer::qt_metacall (this=0x836c3d8, 
    _c=QMetaObject::InvokeMetaMethod, _id=0, _a=0xbfda2d74) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim_build/kmail/messagecomposer.moc:68 
#31 0xb7f211f4 in QMetaObject::activate (sender=0x8370e78, 
    from_signal_index=4, to_signal_index=4, argv=<value optimized out>) 
    at kernel/qobject.cpp:3081 
#32 0xb7f21d94 in QMetaObject::activate (sender=0x8370e78, m=0xb7fbfc64, 
    local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3140 
#33 0xb7f2a3c3 in QSingleShotTimer::timeout (this=0x8370e78) 
    at .moc/debug-shared/qtimer.moc:73 
#34 0xb7f2a40c in QSingleShotTimer::timerEvent (this=0x8370e78) 
    at kernel/qtimer.cpp:296 
#35 0xb7f1f269 in QObject::event (this=0x8370e78, e=0x5556) 
    at kernel/qobject.cpp:1086 
#36 0xb5797e8a in QApplicationPrivate::notify_helper (this=0x80656c8, 
    receiver=0x8370e78, e=0xbfda32a8) at kernel/qapplication.cpp:3556 
#37 0xb579977a in QApplication::notify (this=0xbfda35bc, receiver=0x8370e78, 
    e=0xbfda32a8) at kernel/qapplication.cpp:3115 
#38 0xb6b1fb93 in KApplication::notify (this=0xbfda35bc, receiver=0x8370e78, 
    event=0xbfda32a8) 
    at /var/tmp/portage/kde-base/kdelibs-9999.4/work/kdelibs-9999.4/kdeui/kernel/kapplication.cpp:311 
#39 0xb7f0dd7b in QCoreApplication::notifyInternal (this=0xbfda35bc, 
    receiver=0x8370e78, event=0xbfda32a8) at kernel/qcoreapplication.cpp:530 
#40 0xb7f36efb in QTimerInfoList::activateTimers (this=0x806b58c) 
    at kernel/qcoreapplication.h:200 
#41 0xb7f36fd1 in QEventDispatcherUNIX::activateTimers (this=0x8066300) 
    at kernel/qeventdispatcher_unix.cpp:828 
#42 0xb7f379ab in QEventDispatcherUNIX::processEvents (this=0x8066300, 
    flags=@0xbfda3428) at kernel/qeventdispatcher_unix.cpp:890 
#43 0xb5821cce in QEventDispatcherX11::processEvents (this=0x8066300, 
    flags=@0xbfda3454) at kernel/qeventdispatcher_x11.cpp:145 
#44 0xb7f0d191 in QEventLoop::processEvents (this=0xbfda34c0, 
    flags=@0xbfda3488) at kernel/qeventloop.cpp:140 
#45 0xb7f0d29a in QEventLoop::exec (this=0xbfda34c0, flags=@0xbfda34c8) 
    at kernel/qeventloop.cpp:186 
#46 0xb7f0f626 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:759 
#47 0xb5797487 in QApplication::exec () at kernel/qapplication.cpp:3053 
#48 0x0804a8de in main (argc=) 
    at /var/tmp/portage/kde-base/kdepim-9999.4/work/kdepim-9999.4/kmail/main.cpp:131 
#49 0xb50e2fdc in __libc_start_main (main=0x804a720 <main>, argc=4, 
    ubp_av=0xbfda36a4, init=0x804af60 <__libc_csu_init>, 
    fini=0x804af50 <__libc_csu_fini>, rtld_fini=0xb7fd1100 <_dl_fini>, 
    stack_end=0xbfda369c) at libc-start.c:229 
#50 0x0804a021 in _start () 
#0  0xffffe410 in __kernel_vsyscall ()