Getting this exact stracktrace too on Arch Linux testing with 15.08.2 packages. Closing crash handler makes kmail keep working, but it is recurring.

Same issue here with Arch Linux, except that emails can only be checked each time akonadi server is restarted. The akonadi server log is full of errors:

"Cannot connect to agent instance with identifier 'akonadi_maildir_resource_0', error message: 'Could not get owner of name 'org.freedesktop.Akonadi.Resource.akonadi_maildir_resource_0': no such name'" 

MySQL server log does not contain errors.

Created attachment 95293 [details]
New crash information added by DrKonqi

akonadi_imap_resource (4.89.0) using Qt 5.4.2

- What I was doing when the application crashed:

kmail was running in the background. so it was an automated check of the imap server for new mails.
since upgrading to kubuntu 15.10 I experience this about once a day.

-- Backtrace (Reduced):
#6  0x00007f652070c693 in Akonadi::Entity::id (this=this@entry=0x7f651dbe4518 <QArrayData::shared_null+24>) at ../../../../akonadi/src/core/entity.cpp:72
#7  0x000000000045833e in ImapResourceBase::retrieveItems (this=this@entry=0x15e6870, col=...) at ../../../resources/imap/imapresourcebase.cpp:435
#8  0x00007f6520ab132d in Akonadi::ResourceBasePrivate::slotItemRetrievalCollectionFetchDone (this=<optimized out>, job=0x166ccf0) at ../../../../akonadi/src/agentbase/resourcebase.cpp:954
#9  0x00007f6520ab3200 in Akonadi::ResourceBase::qt_static_metacall (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>) at ./moc_resourcebase.cpp:294
[...]
#11 0x00007f651ee648d2 in KJob::result (this=this@entry=0x166ccf0, _t1=_t1@entry=0x166ccf0) at ./moc_kjob.cpp:552

Created attachment 95333 [details]
New crash information added by DrKonqi

akonadi_imap_resource (4.89.0) using Qt 5.4.2

KMail running in the background, no user input

-- Backtrace (Reduced):
#6  0x00007fe7ddb9c693 in Akonadi::Entity::id (this=this@entry=0x7fe7db074518 <QArrayData::shared_null+24>) at ../../../../akonadi/src/core/entity.cpp:72
#7  0x000000000045833e in ImapResourceBase::retrieveItems (this=this@entry=0xb670b0, col=...) at ../../../resources/imap/imapresourcebase.cpp:435
#8  0x00007fe7ddf4132d in Akonadi::ResourceBasePrivate::slotItemRetrievalCollectionFetchDone (this=<optimized out>, job=0xb22640) at ../../../../akonadi/src/agentbase/resourcebase.cpp:954
#9  0x00007fe7ddf43200 in Akonadi::ResourceBase::qt_static_metacall (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>) at ./moc_resourcebase.cpp:294
[...]
#11 0x00007fe7dc2f48d2 in KJob::result (this=this@entry=0xb22640, _t1=_t1@entry=0xb22640) at ./moc_kjob.cpp:552

Also had the same backtrace on Ubuntu 15.10:

Application: Akonadi Resource (akonadi_imap_resource), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fbbef562840 (LWP 5821))]

Thread 5 (Thread 0x7fbbec8a5700 (LWP 5822)):
#0  0x00007fbbfeebc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fbbfa684bd2 in ?? () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#2  0x00007fbbfa68674f in xcb_wait_for_event () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#3  0x00007fbbef052a39 in QXcbEventReader::run (this=0xea2fe0) at qxcbconnection.cpp:1105
#4  0x00007fbbff7c62be in QThreadPrivate::start (arg=0xea2fe0) at thread/qthread_unix.cpp:337
#5  0x00007fbbfa8a36aa in start_thread (arg=0x7fbbec8a5700) at pthread_create.c:333
#6  0x00007fbbfeec7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 4 (Thread 0x7fbbe5a3c700 (LWP 5827)):
#0  0x00007fbbf9d8a869 in g_mutex_lock () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#1  0x00007fbbf9d45789 in g_main_context_prepare () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fbbf9d4611b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fbbf9d462fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fbbff9fd29b in QEventDispatcherGlib::processEvents (this=0x7fbbe00008e0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#5  0x00007fbbff9a375a in QEventLoop::exec (this=this@entry=0x7fbbe5a3bd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#6  0x00007fbbff7c13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#7  0x00007fbbff7c62be in QThreadPrivate::start (arg=0xffcdd0) at thread/qthread_unix.cpp:337
#8  0x00007fbbfa8a36aa in start_thread (arg=0x7fbbe5a3c700) at pthread_create.c:333
#9  0x00007fbbfeec7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 3 (Thread 0x7fbbe523b700 (LWP 5828)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x00007fbbff7c7496 in QWaitConditionPrivate::wait_relative (time=30000, this=0x7fbbe0019840) at thread/qwaitcondition_unix.cpp:126
#2  QWaitConditionPrivate::wait (time=30000, this=0x7fbbe0019840) at thread/qwaitcondition_unix.cpp:134
#3  QWaitCondition::wait (this=this@entry=0x7fbbe0019300, mutex=mutex@entry=0x7fbbe0019440, time=30000) at thread/qwaitcondition_unix.cpp:208
#4  0x00007fbbff7c3003 in QThreadPoolThread::run (this=0x7fbbe00192f0) at thread/qthreadpool.cpp:127
#5  0x00007fbbff7c62be in QThreadPrivate::start (arg=0x7fbbe00192f0) at thread/qthread_unix.cpp:337
#6  0x00007fbbfa8a36aa in start_thread (arg=0x7fbbe523b700) at pthread_create.c:333
#7  0x00007fbbfeec7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7fbbdffff700 (LWP 5836)):
#0  0x00007fbbfeeb849d in read () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fbbf658af75 in ?? () from /usr/lib/nvidia-352-updates/tls/libnvidia-tls.so.352.41
#2  0x00007fbbf9d894e0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fbbf9d45cd4 in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fbbf9d46190 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007fbbf9d462fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#6  0x00007fbbff9fd29b in QEventDispatcherGlib::processEvents (this=0x7fbbd40008e0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#7  0x00007fbbff9a375a in QEventLoop::exec (this=this@entry=0x7fbbdfffed80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#8  0x00007fbbff7c13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#9  0x00007fbbff7c62be in QThreadPrivate::start (arg=0xffdf80) at thread/qthread_unix.cpp:337
#10 0x00007fbbfa8a36aa in start_thread (arg=0x7fbbdffff700) at pthread_create.c:333
#11 0x00007fbbfeec7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7fbbef562840 (LWP 5821)):
[KCrash Handler]
#6  0x00007fbc0259d693 in Akonadi::Entity::id (this=this@entry=0x7fbbffa75518 <QArrayData::shared_null+24>) at ../../../../akonadi/src/core/entity.cpp:72
#7  0x000000000045833e in ImapResourceBase::retrieveItems (this=this@entry=0xfb1da0, col=...) at ../../../resources/imap/imapresourcebase.cpp:435
#8  0x00007fbc0294232d in Akonadi::ResourceBasePrivate::slotItemRetrievalCollectionFetchDone (this=<optimized out>, job=0x104bcb0) at ../../../../akonadi/src/agentbase/resourcebase.cpp:954
#9  0x00007fbc02944200 in Akonadi::ResourceBase::qt_static_metacall (_o=_o@entry=0xfb1da0, _c=_c@entry=QMetaObject::InvokeMetaMethod, _id=_id@entry=42, _a=_a@entry=0x7ffc258f6b30) at ./moc_resourcebase.cpp:294
#10 0x00007fbbff9d678a in QMetaObject::activate (sender=sender@entry=0x104bcb0, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=3, argv=argv@entry=0x7ffc258f6b30) at kernel/qobject.cpp:3717
#11 0x00007fbbff9d6f87 in QMetaObject::activate (sender=sender@entry=0x104bcb0, m=m@entry=0x7fbc00f3f5c0 <KJob::staticMetaObject>, local_signal_index=local_signal_index@entry=3, argv=argv@entry=0x7ffc258f6b30) at kernel/qobject.cpp:3582
#12 0x00007fbc00cf58d2 in KJob::result (this=this@entry=0x104bcb0, _t1=_t1@entry=0x104bcb0) at ./moc_kjob.cpp:552
#13 0x00007fbc00cf645a in KJob::emitResult (this=this@entry=0x104bcb0) at ../../../src/lib/jobs/kjob.cpp:294
#14 0x00007fbc0262e3b3 in Akonadi::JobPrivate::delayedEmitResult (this=<optimized out>) at ../../../../akonadi/src/core/jobs/job.cpp:153
#15 Akonadi::Job::qt_static_metacall (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>) at ./moc_job.cpp:107
#16 0x00007fbbff9d7651 in QObject::event (this=0x104bcb0, e=<optimized out>) at kernel/qobject.cpp:1245
#17 0x00007fbc002f4b8c in QApplicationPrivate::notify_helper (this=this@entry=0xe76230, receiver=receiver@entry=0x104bcb0, e=e@entry=0xfcfcb0) at kernel/qapplication.cpp:3720
#18 0x00007fbc002fa230 in QApplication::notify (this=0x7ffc258f7160, receiver=0x104bcb0, e=0xfcfcb0) at kernel/qapplication.cpp:3503
#19 0x00007fbbff9a5f1b in QCoreApplication::notifyInternal (this=0x7ffc258f7160, receiver=0x104bcb0, event=event@entry=0xfcfcb0) at kernel/qcoreapplication.cpp:935
#20 0x00007fbbff9a8057 in QCoreApplication::sendEvent (event=0xfcfcb0, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:228
#21 QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0xe6d530) at kernel/qcoreapplication.cpp:1552
#22 0x00007fbbff9a8588 in QCoreApplication::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0) at kernel/qcoreapplication.cpp:1410
#23 0x00007fbbff9fce73 in postEventSourceDispatch (s=0xec7af0) at kernel/qeventdispatcher_glib.cpp:271
#24 0x00007fbbf9d45ff7 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#25 0x00007fbbf9d46250 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#26 0x00007fbbf9d462fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#27 0x00007fbbff9fd27f in QEventDispatcherGlib::processEvents (this=0xed18e0, flags=...) at kernel/qeventdispatcher_glib.cpp:418
#28 0x00007fbbff9a375a in QEventLoop::exec (this=this@entry=0x7ffc258f70d0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#29 0x00007fbbff9ab2cc in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1188
#30 0x00007fbbffd4100c in QGuiApplication::exec () at kernel/qguiapplication.cpp:1510
#31 0x00007fbc002f1025 in QApplication::exec () at kernel/qapplication.cpp:2956
#32 0x00007fbc0293e21a in Akonadi::ResourceBase::init (r=r@entry=0xfb1da0) at ../../../../akonadi/src/agentbase/resourcebase.cpp:602
#33 0x000000000043eaf3 in Akonadi::ResourceBase::init<ImapResource> (argc=<optimized out>, argv=<optimized out>) at /usr/include/KF5/AkonadiAgentBase/resourcebase.h:193
#34 0x00007fbbfede1a40 in __libc_start_main (main=0x43e950 <main(int, char**)>, argc=3, argv=0x7ffc258f7278, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffc258f7268) at libc-start.c:289
#35 0x000000000043e9b9 in _start ()

Created attachment 95463 [details]
New crash information added by DrKonqi

akonadi_imap_resource (4.89.0) using Qt 5.4.2

- What I was doing when the application crashed:

Practically I was doing nothing, but listening to spotify. This happens about 10 times per day.

-- Backtrace (Reduced):
#6  0x00007fb5fbd4d693 in Akonadi::Entity::id (this=this@entry=0x7fb5f9225518 <QArrayData::shared_null+24>) at ../../../../akonadi/src/core/entity.cpp:72
#7  0x000000000045833e in ImapResourceBase::retrieveItems (this=this@entry=0x22354e0, col=...) at ../../../resources/imap/imapresourcebase.cpp:435
#8  0x00007fb5fc0f232d in Akonadi::ResourceBasePrivate::slotItemRetrievalCollectionFetchDone (this=<optimized out>, job=0x227aff0) at ../../../../akonadi/src/agentbase/resourcebase.cpp:954
#9  0x00007fb5fc0f4200 in Akonadi::ResourceBase::qt_static_metacall (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>) at ./moc_resourcebase.cpp:294
[...]
#11 0x00007fb5fa4a58d2 in KJob::result (this=this@entry=0x227aff0, _t1=_t1@entry=0x227aff0) at ./moc_kjob.cpp:552

More information: This never crashed on the Ubuntu 15.04 version of akonadi. I have two imap inboxes, an outlook.com one and a big gmail inbox. The latter is the one that crashes now. I just have to wait for about an hour, sometimes even less. It will crash 4-8 times a day.

*** This bug has been confirmed by popular vote. ***

Wow, this bug stinks. I have to restart the Akonadi service everytime it crashes, otherwise I feel like back in the 90's when you got only one email per day.

This happens on both my Kubuntu Wily Werewolf machines, QT 5.4.2, which both have 3 imap accounts. 
The crashes are so chronic that I doubt any of this code has been tested with multiple accounts. Can a maintainer from Kontact/akonadi please comment? This issue needs some love.

I also have 3 IMAP accounts and it is indeed chronic to the point I've had to turn off periodic checking and use my phone for notifications instead

Since no one seems to acknowledge that this is an important bug that needs to be fixed, here is a script for people who can't wait. Replace akonadi_imap_resource_3 with the name of the akonadi resource that crashes.

$ cat imap_resource_respawn
#!/bin/bash

while [ /bin/true ]
do
        PID=`pgrep -f  "/usr/bin/akonadi_imap_resource --identifier akonadi_imap_resource_3"`
        if [ -z $PID ]
        then
                echo process $PID died. Respawning.
                /usr/bin/akonadi_imap_resource --identifier akonadi_imap_resource_3&
        fi
        sleep 10s
done

Created attachment 97141 [details]
New crash information added by DrKonqi

akonadi_imap_resource (4.89.0) using Qt 5.4.2

- What I was doing when the application crashed:
Watching Youtube videos when mail was checked in the background by Kontact.

-- Backtrace (Reduced):
#6  0x00007fda6cc31693 in Akonadi::Entity::id (this=this@entry=0x7fda6a109518 <QArrayData::shared_null+24>) at ../../../../akonadi/src/core/entity.cpp:72
#7  0x000000000045833e in ImapResourceBase::retrieveItems (this=this@entry=0x194e430, col=...) at ../../../resources/imap/imapresourcebase.cpp:435
#8  0x00007fda6cfd632d in Akonadi::ResourceBasePrivate::slotItemRetrievalCollectionFetchDone (this=<optimized out>, job=0x1ad10b0) at ../../../../akonadi/src/agentbase/resourcebase.cpp:954
#9  0x00007fda6cfd8200 in Akonadi::ResourceBase::qt_static_metacall (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>) at ./moc_resourcebase.cpp:294
[...]
#11 0x00007fda6b3898d2 in KJob::result (this=this@entry=0x1ad10b0, _t1=_t1@entry=0x1ad10b0) at ./moc_kjob.cpp:552

Created attachment 97363 [details]
New crash information added by DrKonqi

akonadi_imap_resource (4.89.0) using Qt 5.4.2

- What I was doing when the application crashed:
Checking and reading mail.
I have Google Mail and Godaddy Email set up in the client.

-- Backtrace (Reduced):
#6  0x00007f789e50b693 in Akonadi::Entity::id (this=this@entry=0x7f789b9e3518 <QArrayData::shared_null+24>) at ../../../../akonadi/src/core/entity.cpp:72
#7  0x000000000045833e in ImapResourceBase::retrieveItems (this=this@entry=0x239b000, col=...) at ../../../resources/imap/imapresourcebase.cpp:435
#8  0x00007f789e8b032d in Akonadi::ResourceBasePrivate::slotItemRetrievalCollectionFetchDone (this=<optimized out>, job=0x240b8f0) at ../../../../akonadi/src/agentbase/resourcebase.cpp:954
#9  0x00007f789e8b2200 in Akonadi::ResourceBase::qt_static_metacall (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>) at ./moc_resourcebase.cpp:294
[...]
#11 0x00007f789cc638d2 in KJob::result (this=this@entry=0x240b8f0, _t1=_t1@entry=0x240b8f0) at ./moc_kjob.cpp:552

Hi,

this should be fixed since KDE Applications 15.12. Can you please confirm whether you can still reproduce in 15.12 or newer?

Yes, it seems to be fixed already. You can close it. If it shows up again, someone can reopen it...

*** Bug 361608 has been marked as a duplicate of this bug. ***