Version:           1.8.2 (using KDE 3.5 (RC1), Debian Package 4:3.5-rc1-1 (testing/unstable))
Compiler:          Target: i486-linux-gnu
OS:                Linux (i686) release 2.6.12-1-686-smp

Yesterday I've upgraded KDE from 3.4.3 to 3.5-rc1 on my Debian Unstable.
It appears that everything is working fine. Except Kontact (or Kmail).
Since that I can't send email using Kontact anymore.

What is strange is that sometimes it works, but usually not.

Bellow are the backtrace from gdb:

nees@est01:~$ kontact  
nees@est01:~$ QWidget::setMaximumSize: (unnamed/RecipientComboBox) The largest allowed size is (32767,32767)
*** KMail got signal 11 (Crashing)
KCrash: Application 'kontact' crashing...

nees@est01:~$ cat tmp/kontact-kmail-backtrace.txt 
(no debugging symbols found)
Using host libthread_db library "/lib/tls/libthread_db.so.1".
(no debugging symbols found)
(no debugging symbols found)
...
...
...
(no debugging symbols found)
(no debugging symbols found)
[Thread debugging using libthread_db enabled]
[New Thread -1241229632 (LWP 10049)]
(no debugging symbols found)
(no debugging symbols found)
...
...
...
(no debugging symbols found)
(no debugging symbols found)
[KCrash handler]
#3  0xb7965c01 in __gnu_cxx::__pool<true>::_M_reclaim_block ()
   from /usr/lib/libstdc++.so.6
#4  0xb5786ddf in __gnu_cxx::__mt_alloc<GpgME::Key, __gnu_cxx::__common_pool_policy<__gnu_cxx::__pool, true> >::deallocate () from /usr/lib/libkmailprivate.so
#5  0xb591c0ce in Kleo::KeyResolver::lookup () from /usr/lib/libkmailprivate.so
#6  0xb591d3fb in Kleo::KeyResolver::setSigningKeys ()
   from /usr/lib/libkmailprivate.so
#7  0xb590e479 in MessageComposer::adjustCryptFlags ()
   from /usr/lib/libkmailprivate.so
#8  0xb591750f in AdjustCryptFlagsJob::execute ()
   from /usr/lib/libkmailprivate.so
#9  0xb590b815 in MessageComposer::slotDoNextJob ()
   from /usr/lib/libkmailprivate.so
#10 0xb590b84e in MessageComposer::qt_invoke ()
   from /usr/lib/libkmailprivate.so
#11 0xb6d56c5f in QObject::activate_signal () from /usr/lib/libqt-mt.so.3
#12 0xb70e75a5 in QSignal::signal () from /usr/lib/libqt-mt.so.3
#13 0xb6d74b30 in QSignal::activate () from /usr/lib/libqt-mt.so.3
#14 0xb6d7c444 in QSingleShotTimer::event () from /usr/lib/libqt-mt.so.3
#15 0xb6cec778 in QApplication::internalNotify () from /usr/lib/libqt-mt.so.3
#16 0xb6cec996 in QApplication::notify () from /usr/lib/libqt-mt.so.3
#17 0xb73e6d8c in KApplication::notify () from /usr/lib/libkdecore.so.4
#18 0xb6c7c665 in QApplication::sendEvent () from /usr/lib/libqt-mt.so.3
#19 0xb6cdda44 in QEventLoop::activateTimers () from /usr/lib/libqt-mt.so.3
#20 0xb6c903f8 in QEventLoop::processEvents () from /usr/lib/libqt-mt.so.3
#21 0xb6d04ea2 in QEventLoop::enterLoop () from /usr/lib/libqt-mt.so.3
#22 0xb6d04dcb in QEventLoop::exec () from /usr/lib/libqt-mt.so.3
#23 0xb6ceb305 in QApplication::exec () from /usr/lib/libqt-mt.so.3
#24 0x0805a09d in ?? ()
#25 0xbfe7cf80 in ?? ()
#26 0x00000001 in ?? ()
#27 0x00000001 in ?? ()
#28 0x00000000 in ?? ()