*** Bug 200382 has been marked as a duplicate of this bug. ***

There are 2 different bugs here.  The first is, why did sending hang?  The second is the crash.

I had yet another variant of this bug happen to me today.

1. Composed message and clicked Send.
2. Sending hanged with composer window grayed out.
3. "Send Queued Messages" (no effect)
4. Canceled hung background send operation.
5. "Send Queued Messages" (message was sent)
6. Closed still-grayed-out composer window.
7. Browsed through another couple of mail folders.
8. Left KMail alone.
9. Some time later (probably at the next mail check), KMail spontaneously crashed with the following backtrace:

Application: KMail (kmail), signal: Segmentation fault
[KCrash Handler]
#5  0x00007f3074207260 in KMMsgBase::asIndexString (this=0x266ddc0, length=@0x7fff3112213c) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/kmmsgbase.cpp:1155
#6  0x00007f30743a3cf2 in KMFolderIndex::writeMessages (this=0xa16560, msg=<value optimized out>, flush=false, indexStream=0x379ba20)
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/kmfolderindex.cpp:502
#7  0x00007f30743a42e2 in KMFolderIndex::writeIndex (this=0xa16560, createEmptyIndex=false) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/kmfolderindex.cpp:111
#8  0x00007f3074191a21 in FolderStorage::qt_metacall (this=0xa16560, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff31122450)
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/folderstorage.moc:142
#9  0x00007f30743a234a in KMFolderIndex::qt_metacall (this=0x7fff31122090, _c=40295872, _id=823271584, _a=0x0)
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/kmfolderindex.moc:63
#10 0x00007f3074282465 in KMFolderMaildir::qt_metacall (this=0x7fff31122090, _c=40295872, _id=823271584, _a=0x0)
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/kmfoldermaildir.moc:61
#11 0x00007f306f62cf9e in QMetaObject::activate (sender=0xa0e6a0, from_signal_index=<value optimized out>, to_signal_index=4, argv=0x0) at kernel/qobject.cpp:3101
#12 0x00007f306f62e433 in QObject::event (this=0xa0e6a0, e=0x266ddc0) at kernel/qobject.cpp:1066
#13 0x00007f306fd007ed in QApplicationPrivate::notify_helper (this=0x7cf320, receiver=0xa0e6a0, e=0x7fff31122b20) at kernel/qapplication.cpp:4056
#14 0x00007f306fd0330a in QApplication::notify (this=0x7fff31125230, receiver=0xa0e6a0, e=0x7fff31122b20) at kernel/qapplication.cpp:4021
#15 0x00007f30750b09cb in KApplication::notify (this=0x7fff31125230, receiver=0xa0e6a0, event=0x7fff31122b20)
    at /var/tmp/portage/kde-base/kdelibs-4.3.0/work/kdelibs-4.3.0/kdeui/kernel/kapplication.cpp:302
#16 0x00007f306f619c9b in QCoreApplication::notifyInternal (this=0x7fff31125230, receiver=0xa0e6a0, event=0x7fff31122b20) at kernel/qcoreapplication.cpp:606
#17 0x00007f306f648d05 in QTimerInfoList::activateTimers (this=0x7d16c0) at kernel/qcoreapplication.h:213
#18 0x00007f306f645dbd in timerSourceDispatch (source=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:165
#19 0x00007f3067af4d1d in g_main_dispatch (context=0x7d1000) at gmain.c:1824
#20 0x00007f3067af6aad in g_main_context_iterate (context=0x7d1000, block=1, dispatch=1, self=<value optimized out>) at gmain.c:2377
#21 0x00007f3067af6c0c in IA__g_main_context_iteration (context=0x7d1000, may_block=1) at gmain.c:2518
#22 0x00007f306f645d1f in QEventDispatcherGlib::processEvents (this=0x7990d0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#23 0x00007f306fd9da6f in QGuiEventDispatcherGlib::processEvents (this=0x7fff31122090, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#24 0x00007f306f618932 in QEventLoop::processEvents (this=<value optimized out>, flags={i = 823274912}) at kernel/qeventloop.cpp:149
#25 0x00007f306f618dbd in QEventLoop::exec (this=0x7fff31122f00, flags={i = 823275472}) at kernel/qeventloop.cpp:197
#26 0x00007f3075149b98 in KWallet::Wallet::openWallet (name=@0x7fff31123020, w=<value optimized out>, ot=KWallet::Wallet::Synchronous)
    at /var/tmp/portage/kde-base/kdelibs-4.3.0/work/kdelibs-4.3.0/kdeui/util/kwallet.cpp:252
#27 0x00007f306ae6747d in MailTransport::TransportManager::wallet (this=0x7d4810) at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/transportmanager.cpp:420
#28 0x00007f306ae5d59d in MailTransport::Transport::readPassword (this=0x833240) at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/transport.cpp:245
#29 0x00007f306ae67a2a in MailTransport::TransportManager::loadPasswords (this=0x7d4810) at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/transportmanager.cpp:445
#30 0x00007f306ae5c86d in MailTransport::Transport::password (this=0x6e9f660) at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/transport.cpp:76
#31 0x00007f306ae6ffe6 in MailTransport::SmtpJob::startSmtpJob (this=0x7422d30) at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/smtpjob.cpp:159
#32 0x00007f306ae7113a in MailTransport::SmtpJob::doStart (this=0x7422d30) at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/smtpjob.cpp:114
#33 0x00007f306ae656bd in MailTransport::TransportJob::start (this=0x7422d30) at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/transportjob.cpp:129
#34 0x00007f30741c68fc in KMSender::doSendMsg (this=0xa8e6c0) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/kmsender.cpp:592
#35 0x00007f30741c814c in KMSender::doSendQueued (this=0xa8e6c0, customTransport=@0x7fff31124040) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/kmsender.cpp:244
#36 0x00007f30741c4705 in KMSender::doSend (this=0xa8e6c0, aMsg=0x266ddc0, sendNow=1) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/messagesender.h:77
#37 0x00007f307415038b in KMComposeWin::slotContinueDoSend (this=0x18ab090, sentOk=<value optimized out>) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/messagesender.h:65
#38 0x00007f3074150bcc in KMComposeWin::qt_metacall (this=0x18ab090, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff311243c0)
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/kmcomposewin.moc:313
#39 0x00007f306f62cf9e in QMetaObject::activate (sender=0x18ab090, from_signal_index=<value optimized out>, to_signal_index=50, argv=0x0) at kernel/qobject.cpp:3101
#40 0x00007f307412171d in KMComposeWin::slotComposerDone (this=0x18ab090, rc=true) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/kmcomposewin.moc:331
#41 0x00007f3074150be4 in KMComposeWin::qt_metacall (this=0x18ab090, _c=QMetaObject::InvokeMetaMethod, _id=<value optimized out>, _a=0x7fff31124530)
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/kmcomposewin.moc:312
#42 0x00007f306f62cf9e in QMetaObject::activate (sender=0x43d2900, from_signal_index=<value optimized out>, to_signal_index=4, argv=0x0) at kernel/qobject.cpp:3101
#43 0x00007f3074406bcc in MessageComposer::emitDone (this=0x43d2900, ok=true) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/messagecomposer.moc:82
#44 0x00007f3074406d4f in MessageComposer::doNextJob (this=0x43d2900) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/messagecomposer.cpp:393
#45 0x00007f3074406d89 in MessageComposer::slotDoNextJob (this=0x43d2900) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/messagecomposer.cpp:440
#46 0x00007f3074406ebd in MessageComposer::qt_metacall (this=0x43d2900, _c=QMetaObject::InvokeMetaMethod, _id=3, _a=0x7fff311246d0)
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/messagecomposer.moc:70
#47 0x00007f306f62cf9e in QMetaObject::activate (sender=0x43f6530, from_signal_index=<value optimized out>, to_signal_index=4, argv=0x0) at kernel/qobject.cpp:3101
#48 0x00007f306f638bca in QSingleShotTimer::timerEvent (this=0x43f6530) at .moc/release-shared/qtimer.moc:76
#49 0x00007f306f62e433 in QObject::event (this=0x43f6530, e=0x266ddc0) at kernel/qobject.cpp:1066
#50 0x00007f306fd007ed in QApplicationPrivate::notify_helper (this=0x7cf320, receiver=0x43f6530, e=0x7fff31124db0) at kernel/qapplication.cpp:4056
#51 0x00007f306fd0330a in QApplication::notify (this=0x7fff31125230, receiver=0x43f6530, e=0x7fff31124db0) at kernel/qapplication.cpp:4021
#52 0x00007f30750b09cb in KApplication::notify (this=0x7fff31125230, receiver=0x43f6530, event=0x7fff31124db0)
    at /var/tmp/portage/kde-base/kdelibs-4.3.0/work/kdelibs-4.3.0/kdeui/kernel/kapplication.cpp:302
#53 0x00007f306f619c9b in QCoreApplication::notifyInternal (this=0x7fff31125230, receiver=0x43f6530, event=0x7fff31124db0) at kernel/qcoreapplication.cpp:606
#54 0x00007f306f648d05 in QTimerInfoList::activateTimers (this=0x7d16c0) at kernel/qcoreapplication.h:213
#55 0x00007f306f645dbd in timerSourceDispatch (source=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:165
#56 0x00007f3067af4d1d in g_main_dispatch (context=0x7d1000) at gmain.c:1824
#57 0x00007f3067af6aad in g_main_context_iterate (context=0x7d1000, block=1, dispatch=1, self=<value optimized out>) at gmain.c:2377
#58 0x00007f3067af6c0c in IA__g_main_context_iteration (context=0x7d1000, may_block=1) at gmain.c:2518
#59 0x00007f306f645d1f in QEventDispatcherGlib::processEvents (this=0x7990d0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:327
#60 0x00007f306fd9da6f in QGuiEventDispatcherGlib::processEvents (this=0x7fff31122090, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#61 0x00007f306f618932 in QEventLoop::processEvents (this=<value optimized out>, flags={i = 823283760}) at kernel/qeventloop.cpp:149
#62 0x00007f306f618dbd in QEventLoop::exec (this=0x7fff31125080, flags={i = 823283856}) at kernel/qeventloop.cpp:197
#63 0x00007f306f61cbbc in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#64 0x0000000000403361 in main (argc=<value optimized out>, argv=<value optimized out>) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/main.cpp:146

I just had this happen again.  This time, instead of waiting to get a backtrace until after the inevitable crash, I attached gdb to the running process just after I clicked Send and observed the composer window to disable but not to close.  The "sending mail" background task is stuck at 0%, as is always the case in this scenario.

For what it's worth, my wallet was already open at the time I clicked Send, but I had forcibly closed my wallet and reopened it previously without restarting KMail.  In other words:

1. Start KMail.
2. Enter password in KWallet popup to open wallet.
3. Force wallet closed.
4. Reopen wallet by accessing it from another application (e.g., Konqueror).
5. Attempt to send a message in KMail.

I have no idea whether this sequence has any significance to this bug whatsoever, but I figured it might be worth mentioning since there are some KWallet calls in the backtrace.

Here's the backtrace (there's only one thread):

#0  0x00007f953f2cf426 in __poll (fds=0x1af6830, nfds=10, timeout=49) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00007f953856e86a in g_main_context_iterate (context=0x872000, block=1, dispatch=1, self=<value optimized out>)
    at gmain.c:2768                                                                                                 
#2  0x00007f953856ec0c in IA__g_main_context_iteration (context=0x872000, may_block=1) at gmain.c:2518              
#3  0x00007f95400bdd1f in QEventDispatcherGlib::processEvents (this=0x83a0d0, flags=<value optimized out>)          
    at kernel/qeventdispatcher_glib.cpp:327                                                                         
#4  0x00007f95408155be in QGuiEventDispatcherGlib::processEvents (this=0x1af6830, flags=<value optimized out>)      
    at kernel/qguieventdispatcher_glib.cpp:202                                                                      
#5  0x00007f9540090932 in QEventLoop::processEvents (this=<value optimized out>, flags={i = 249165136})             
    at kernel/qeventloop.cpp:149                                                                                    
#6  0x00007f9540090dbd in QEventLoop::exec (this=0x7fff0ed9f6b0, flags={i = 249165696}) at kernel/qeventloop.cpp:197
#7  0x00007f9545bc1b98 in KWallet::Wallet::openWallet (name=@0x7fff0ed9f7d0, w=<value optimized out>,               
    ot=KWallet::Wallet::Synchronous)                                                                                
    at /var/tmp/portage/kde-base/kdelibs-4.3.0/work/kdelibs-4.3.0/kdeui/util/kwallet.cpp:252                        
#8  0x00007f953b8df47d in MailTransport::TransportManager::wallet (this=0x8d57f0)                                   
    at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/transportmanager.cpp:420      
#9  0x00007f953b8d559d in MailTransport::Transport::readPassword (this=0x874ad0)                                    
    at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/transport.cpp:245             
#10 0x00007f953b8dfa2a in MailTransport::TransportManager::loadPasswords (this=0x8d57f0)                            
    at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/transportmanager.cpp:445      
#11 0x00007f953b8d486d in MailTransport::Transport::password (this=0x357dce0)                                       
    at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/transport.cpp:76              
#12 0x00007f953b8e7fe6 in MailTransport::SmtpJob::startSmtpJob (this=0x8c83e0)                                      
    at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/smtpjob.cpp:159               
#13 0x00007f953b8e913a in MailTransport::SmtpJob::doStart (this=0x8c83e0)                                           
    at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/smtpjob.cpp:114               
#14 0x00007f953b8dd6bd in MailTransport::TransportJob::start (this=0x8c83e0)                                        
    at /var/tmp/portage/kde-base/kdepimlibs-4.3.0/work/kdepimlibs-4.3.0/mailtransport/transportjob.cpp:129          
#15 0x00007f9544c3e8fc in KMSender::doSendMsg (this=0xb2b810)                                                       
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/kmsender.cpp:592                                
#16 0x00007f9544c4014c in KMSender::doSendQueued (this=0xb2b810, customTransport=@0x7fff0eda07f0)                   
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/kmsender.cpp:244                                
#17 0x00007f9544c3c705 in KMSender::doSend (this=0xb2b810, aMsg=0x24121b0, sendNow=1)                               
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/messagesender.h:77                              
#18 0x00007f9544bc838b in KMComposeWin::slotContinueDoSend (this=0x2d046e0, sentOk=<value optimized out>)           
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/messagesender.h:65                              
#19 0x00007f9544bc8bcc in KMComposeWin::qt_metacall (this=0x2d046e0, _c=QMetaObject::InvokeMetaMethod,              
    _id=<value optimized out>, _a=0x7fff0eda0b70)                                                                   
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/kmcomposewin.moc:313                      
#20 0x00007f95400a4f9e in QMetaObject::activate (sender=0x2d046e0, from_signal_index=<value optimized out>,         
    to_signal_index=50, argv=0xffffffffffffffff) at kernel/qobject.cpp:3101                                         
#21 0x00007f9544b9971d in KMComposeWin::slotComposerDone (this=0x2d046e0, rc=true)                                  
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/kmcomposewin.moc:331                      
#22 0x00007f9544bc8be4 in KMComposeWin::qt_metacall (this=0x2d046e0, _c=QMetaObject::InvokeMetaMethod,              
    _id=<value optimized out>, _a=0x7fff0eda0ce0)                                                                   
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/kmcomposewin.moc:312                      
#23 0x00007f95400a4f9e in QMetaObject::activate (sender=0xa31ad0, from_signal_index=<value optimized out>,
    to_signal_index=4, argv=0xffffffffffffffff) at kernel/qobject.cpp:3101
#24 0x00007f9544e7ebcc in MessageComposer::emitDone (this=0xa31ad0, ok=true)
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/messagecomposer.moc:82
#25 0x00007f9544e7ed4f in MessageComposer::doNextJob (this=0xa31ad0)
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/messagecomposer.cpp:393
#26 0x00007f9544e7ed89 in MessageComposer::slotDoNextJob (this=0xa31ad0)
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/messagecomposer.cpp:440
#27 0x00007f9544e7eebd in MessageComposer::qt_metacall (this=0xa31ad0, _c=QMetaObject::InvokeMetaMethod, _id=-516,
    _a=0x7fff0eda0e80) at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0_build/kmail/messagecomposer.moc:70
#28 0x00007f95400a4f9e in QMetaObject::activate (sender=0x1826130, from_signal_index=<value optimized out>,
    to_signal_index=4, argv=0xffffffffffffffff) at kernel/qobject.cpp:3101
#29 0x00007f95400b0bca in QSingleShotTimer::timerEvent (this=0x1826130) at .moc/release-shared/qtimer.moc:76
#30 0x00007f95400a6433 in QObject::event (this=0x1826130, e=0xa) at kernel/qobject.cpp:1066
#31 0x00007f9540776fec in QApplicationPrivate::notify_helper (this=0x870320, receiver=0x1826130, e=0x7fff0eda14f0)
    at kernel/qapplication.cpp:4056
#32 0x00007f95407786c8 in QApplication::notify (this=0x7fff0eda1970, receiver=0x1826130, e=0x7fff0eda14f0)
    at kernel/qapplication.cpp:4021
#33 0x00007f9545b289cb in KApplication::notify (this=0x7fff0eda1970, receiver=0x1826130, event=0x7fff0eda14f0)
    at /var/tmp/portage/kde-base/kdelibs-4.3.0/work/kdelibs-4.3.0/kdeui/kernel/kapplication.cpp:302
#34 0x00007f9540091c9b in QCoreApplication::notifyInternal (this=0x7fff0eda1970, receiver=0x1826130,
    event=0x7fff0eda14f0) at kernel/qcoreapplication.cpp:606
#35 0x00007f95400c0d05 in QTimerInfoList::activateTimers (this=0x8726c0) at kernel/qcoreapplication.h:213
#36 0x00007f95400bddbd in timerSourceDispatch (source=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:165
#37 0x00007f953856cd1d in g_main_dispatch (context=0x872000) at gmain.c:1824
#38 0x00007f953856eaad in g_main_context_iterate (context=0x872000, block=1, dispatch=1, self=<value optimized out>)
    at gmain.c:2377
#39 0x00007f953856ec0c in IA__g_main_context_iteration (context=0x872000, may_block=1) at gmain.c:2518
#40 0x00007f95400bdd1f in QEventDispatcherGlib::processEvents (this=0x83a0d0, flags=<value optimized out>)
    at kernel/qeventdispatcher_glib.cpp:327
#41 0x00007f95408155be in QGuiEventDispatcherGlib::processEvents (this=0x1af6830, flags=<value optimized out>)
    at kernel/qguieventdispatcher_glib.cpp:202
#42 0x00007f9540090932 in QEventLoop::processEvents (this=<value optimized out>, flags={i = 249173872})
    at kernel/qeventloop.cpp:149
#43 0x00007f9540090dbd in QEventLoop::exec (this=0x7fff0eda17c0, flags={i = 249173968}) at kernel/qeventloop.cpp:197
#44 0x00007f9540094bbc in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#45 0x0000000000403361 in main (argc=<value optimized out>, argv=<value optimized out>)
    at /var/tmp/portage/kde-base/kmail-4.3.0/work/kmail-4.3.0/kmail/main.cpp:146

I just had this happen again.  It hasn't happened in quite a while, but I now believe I nailed the problem with my last comment.

Earlier this evening, I locked my session using a script I wrote that sends an org.kde.KWallet.closeAllWallets call to org.kde.kwalletd via DBus before locking the session by calling org.freedesktop.ScreenSaver.Lock.  Then when I returned, I unlocked my session and started Kopete, which asked for my wallet password in order to connect.  My wallet was thus reopened.  Then I tried to send a message in KMail, and it hung.  I'm now quite certain there is a problem with reconnecting to a wallet that was forced closed and then reopened, and it manifests itself as this apparent hang in KMail.

Confirmed; closing all open wallets, then having another application open the wallet, then sending mail from KMail results in a crash.  The crash begins with the composer window being deactivated but not closed; closing the composer window causes the crash.  It is possible to leave the window open, send the mail by selecting "send queued messages," and that will not cause the crash.

I use KMail (1.12.2 on KDE 4.3.1 on openSUSE) daily for work and this bug is really really annoying. I repeat this cycle about once a hour:
1) compose mail
2) hit send
3) hit "close window"
4) answer "discard" to question about whether to save the mail
5) go to outbox
6) see KMail crashing
7) open KMail again
8) do "send queued messages" on outbox

I'll try Ben's suggestion when it happens again :)

About Ben's suggestion in my case. I have to first cancel sending mail and after that "send queued messages" really works. But after a while KMail crashes anyway (I'm not sure on what action).

*** Bug 210024 has been marked as a duplicate of this bug. ***

if my bug #210024 is really a duplicate of this one, then triggering it does not require forcibly closing the KWallet, since i almost never do this. perhaps it is triggered whenever the wallet is closed for any reason, including by timeout, then reopened by an application other than KMail.

as in comment #8, Ben's suggestion in comment #6 enables me to send the mail only if i cancel the stuck transfer before i choose Send Queued Messages. subsequently closing the (still disabled) composer window and choosing Discard causes KMail to crash. in this case the crash is not picked up by the KDE Crash Handler.

*** Bug 212822 has been marked as a duplicate of this bug. ***

*** Bug 212904 has been marked as a duplicate of this bug. ***

*** Bug 211881 has been marked as a duplicate of this bug. ***

From bug 217241:
---
What I was doing when the application crashed:
kontact left running over night.  On trying to send an email (by hitting the
send button in the composer window), the window is fadded and the email to be
sent is added to the outbox, but does not get sent.  I hit the x button to
close the email and was presented with a 'save draft' 'discard' 'cancel' dialog
window.  I selected cancel and then kontact crashed.  Upon restarting kontact,
I was given the 'kontact already running' warning window to which I responded
'start anyway'.  The email was still in the out box and sent with out error in
the restarted kontact.

This has happened before (once ever other week), but I can not reliabley
reproduce it.  I have a hunch that it is related to kwallet interactions.  In
all the cases that it has crashed I have first started kopete and opened
kwallet.  The wallet is still open when I attempted to send the email.

*** Bug 217241 has been marked as a duplicate of this bug. ***

*** Bug 238476 has been marked as a duplicate of this bug. ***

This bug appears to have resurfaced in KMail 1.13.5. It doesn't crash anymore, but it simply refuses to send any queued outgoing messages after the wallet has been closed and reopened by another application while KMail is running. Quitting KMail doesn't actually cause it to terminate then, either. I have to send it a SIGTERM and then restart it, and then Send Queued Messages actually works.

*** Bug 262861 has been marked as a duplicate of this bug. ***

*** Bug 280732 has been marked as a duplicate of this bug. ***

Thank you for your report. Kmail1 is currently unmaintained and the code has changed sufficiently in Kmail2 so the backtraces are not really useful anymore. Should you experience the same crash in Kmail 4.8.5 or later, please open a new report for Kmail2. Thank you for your understanding