diff --git a/app/Events/UserConfirmedEvent.php b/app/Events/UserConfirmedEvent.php
new file mode 100644
index 0000000000..f2f1195147
--- /dev/null
+++ b/app/Events/UserConfirmedEvent.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace App\Events;
+
+use App\Group;
+use Illuminate\Broadcasting\Channel;
+use Illuminate\Broadcasting\InteractsWithSockets;
+use Illuminate\Broadcasting\PresenceChannel;
+use Illuminate\Broadcasting\PrivateChannel;
+use Illuminate\Contracts\Broadcasting\ShouldBroadcast;
+use Illuminate\Foundation\Events\Dispatchable;
+use Illuminate\Queue\SerializesModels;
+
+class UserConfirmedEvent
+{
+    use Dispatchable, InteractsWithSockets, SerializesModels;
+
+    public $idevents;
+    public $iduser;
+
+    /**
+     * Create a new event instance.
+     *
+     * @return void
+     */
+    public function __construct($idevents, $iduser)
+    {
+        $this->idevents = $idevents;
+        $this->iduser = $iduser;
+    }
+}
diff --git a/app/Events/UserLeftEvent.php b/app/Events/UserLeftEvent.php
new file mode 100644
index 0000000000..c1a968973b
--- /dev/null
+++ b/app/Events/UserLeftEvent.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace App\Events;
+
+use App\Group;
+use Illuminate\Broadcasting\Channel;
+use Illuminate\Broadcasting\InteractsWithSockets;
+use Illuminate\Broadcasting\PresenceChannel;
+use Illuminate\Broadcasting\PrivateChannel;
+use Illuminate\Contracts\Broadcasting\ShouldBroadcast;
+use Illuminate\Foundation\Events\Dispatchable;
+use Illuminate\Queue\SerializesModels;
+
+class UserLeftEvent
+{
+    use Dispatchable, InteractsWithSockets, SerializesModels;
+
+    public $idevents;
+    public $iduser;
+
+    /**
+     * Create a new event instance.
+     *
+     * @return void
+     */
+    public function __construct($idevents, $iduser)
+    {
+        $this->idevents = $idevents;
+        $this->iduser = $iduser;
+    }
+}
diff --git a/app/EventsUsers.php b/app/EventsUsers.php
index 569923b1f7..23546bc0bd 100644
--- a/app/EventsUsers.php
+++ b/app/EventsUsers.php
@@ -38,6 +38,11 @@ public function volunteer()
         return $this->hasOne(\App\User::class, 'id', 'user');
     }
 
+    public function event()
+    {
+        return $this->hasOne(\App\Party::class, 'id', 'event');
+    }
+
     public function getFullName()
     {
         if (! is_null($this->full_name)) {
diff --git a/app/Http/Controllers/API/EventController.php b/app/Http/Controllers/API/EventController.php
index 12ef1170fc..655bba5d45 100644
--- a/app/Http/Controllers/API/EventController.php
+++ b/app/Http/Controllers/API/EventController.php
@@ -161,9 +161,18 @@ public function addVolunteer(Request $request, $idevents)
             $full_name = null;
         }
 
-        // User is null, this volunteer is either anonymous or no user exists.
+        $eventRole = Role::RESTARTER;
+
         if ($request->has('user') && $request->input('user') !== 'not-registered') {
+            // User is null, this volunteer is either anonymous or no user exists.
             $user = $request->input('user');
+
+            if ($user) {
+                $u = User::find($user);
+
+                // A host of the group who is added to an event becomes a host of the event.
+                $eventRole = $u && Fixometer::userIsHostOfGroup($party->group, $user) ? Role::HOST : Role::RESTARTER;
+            }
         } else {
             $user = null;
         }
@@ -173,7 +182,7 @@ public function addVolunteer(Request $request, $idevents)
             ->where('user', $user)
             ->where('status', '<>', 1)
             ->whereNotNull('status')
-            ->where('role', 4);
+            ->where('role', $eventRole);
         $userWasInvited = $invitedUserQuery->count() == 1;
 
         if ($userWasInvited) {
@@ -186,13 +195,11 @@ public function addVolunteer(Request $request, $idevents)
                 'event' => $idevents,
                 'user' => $user,
                 'status' => 1,
-                'role' => 4,
+                'role' => $eventRole,
                 'full_name' => $full_name,
             ]);
         }
 
-        $party->increment('volunteers');
-
         if (!is_null($volunteer_email_address)) {
             // Send email.
             $from = User::find(Auth::user()->id);
@@ -491,8 +498,6 @@ public function createEventv2(Request $request)
             'role' => Role::HOST,
         ]);
 
-        $party->increment('volunteers');
-
         // Notify relevant users.
         $usersToNotify = Fixometer::usersWhoHavePreference('admin-moderate-event');
         foreach ($party->associatedNetworkCoordinators() as $coordinator) {
diff --git a/app/Http/Controllers/PartyController.php b/app/Http/Controllers/PartyController.php
index 54f1fa38e4..cef20dbe14 100644
--- a/app/Http/Controllers/PartyController.php
+++ b/app/Http/Controllers/PartyController.php
@@ -418,15 +418,12 @@ public function getJoinEvent($event_id)
                                                               ]);
 
 
-                    $event->increment('volunteers');
-
                     $flashData = [];
                     if (! Auth::user()->isInGroup($event->theGroup->idgroups)) {
                         $flashData['prompt-follow-group'] = true;
                     }
 
                     $this->notifyHostsOfRsvp($user_event, $event_id);
-                    $this->addToDiscourseThread($event, Auth::user());
 
                     return redirect()->back()->with($flashData);
                 }
@@ -473,30 +470,6 @@ public function notifyHostsOfRsvp($user_event, $event_id)
         }
     }
 
-    public function addToDiscourseThread($event, $user)
-    {
-        if ($event->discourse_thread) {
-            // We want a host of the event to add the user to the thread.
-            try {
-                $hosts = User::join('events_users', 'events_users.user', '=', 'users.id')
-                    ->where('events_users.event', $event->idevents)
-                    ->where('events_users.role', 3)
-                    ->select('users.*')
-                    ->get();
-            } catch (\Exception $e) {
-                $hosts = null;
-            }
-
-            if (! is_null($hosts) && count($hosts)) {
-                $this->discourseService->addUserToPrivateMessage(
-                    $event->discourse_thread,
-                    $hosts[0]->username,
-                    $user->username
-                );
-            }
-        }
-    }
-
     public static function stats($id)
     {
         $event = Party::where('idevents', $id)->first();
@@ -605,11 +578,6 @@ public function removeVolunteer(Request $request)
                 $delete_user = $volunteer->delete();
 
                 if ($delete_user == 1) {
-                    //If the user accepted the invitation, we decrement
-                    if ($volunteer->status == 1) {
-                        Party::find($event_id)->decrement('volunteers');
-                    }
-
                     //Return JSON
                     $return = [
                         'success' => true,
@@ -750,10 +718,8 @@ public function confirmInvite($event_id, $hash)
 
             // Increment volunteers column to include latest invite
             $event = Party::find($event_id);
-            $event->increment('volunteers');
 
             $this->notifyHostsOfRsvp($user_event, $event_id);
-            $this->addToDiscourseThread($event, Auth::user());
 
             return redirect('/party/view/'.$user_event->event);
         }
@@ -764,7 +730,10 @@ public function confirmInvite($event_id, $hash)
 
     public function cancelInvite($event_id)
     {
-        EventsUsers::where('user', Auth::user()->id)->where('event', $event_id)->delete();
+        // We have to do a loop to avoid the gotcha where bulk delete operations don't invoke observers.
+        foreach (EventsUsers::where('user', Auth::user()->id)->where('event', $event_id)->get() as $delete) {
+            $delete->delete();
+        };
 
         return redirect('/party/view/'.intval($event_id))->with('success', __('events.invite_cancelled'));
     }
@@ -865,7 +834,12 @@ public function deleteEvent($id)
 
         Audits::where('auditable_type', \App\Party::class)->where('auditable_id', $id)->delete();
         Device::where('event', $id)->delete();
-        EventsUsers::where('event', $id)->delete();
+
+        // We have to do a loop to avoid the gotcha where bulk delete operations don't invoke observers.
+        foreach (EventsUsers::where('event', $id)->get() as $delete) {
+            $delete->delete();
+        };
+
         $event->delete();
 
         event(new EventDeleted($event));
diff --git a/app/Listeners/AddUserToDiscourseThreadForEvent.php b/app/Listeners/AddUserToDiscourseThreadForEvent.php
new file mode 100644
index 0000000000..1571d48b4e
--- /dev/null
+++ b/app/Listeners/AddUserToDiscourseThreadForEvent.php
@@ -0,0 +1,50 @@
+<?php
+
+namespace App\Listeners;
+
+use App\Events\UserConfirmedEvent;
+use App\Party;
+use App\Role;
+use App\Services\DiscourseService;
+use App\User;
+use Illuminate\Contracts\Queue\ShouldQueue;
+
+class AddUserToDiscourseThreadForEvent implements ShouldQueue {
+    private $discourseService;
+
+    public function __construct(DiscourseService $discourseService)
+    {
+        $this->discourseService = $discourseService;
+    }
+
+    private function getHost($idevents) {
+        $hosts = User::join('events_users', 'events_users.user', '=', 'users.id')
+            ->where('events_users.event', $idevents)
+            ->where('events_users.role', Role::HOST)
+            ->select('users.*')
+            ->get();
+
+        return $hosts->count() ? $hosts[0] : null;
+    }
+
+    public function handle(UserConfirmedEvent $e) {
+        if ($e->iduser) {
+            $event = Party::find($e->idevents);
+            $user = User::find($e->iduser);
+
+            // Might not exist - timing windows.
+            if ($event && $user && $event->discourse_thread) {
+                // We need a host of the event to add the user to the thread.
+                $host = $this->getHost($event->idevents);
+
+                if ($host) {
+                    $this->discourseService->addUserToPrivateMessage(
+                        $event->discourse_thread,
+                        $host->username,
+                        $user->username
+                    );
+                }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/app/Listeners/RemoveUserFromDiscourseThreadForEvent.php b/app/Listeners/RemoveUserFromDiscourseThreadForEvent.php
new file mode 100644
index 0000000000..d19f093be5
--- /dev/null
+++ b/app/Listeners/RemoveUserFromDiscourseThreadForEvent.php
@@ -0,0 +1,50 @@
+<?php
+
+namespace App\Listeners;
+
+use App\Events\UserLeftEvent;
+use App\Party;
+use App\Role;
+use App\Services\DiscourseService;
+use App\User;
+use Illuminate\Contracts\Queue\ShouldQueue;
+
+class RemoveUserFromDiscourseThreadForEvent implements ShouldQueue {
+    private $discourseService;
+
+    public function __construct(DiscourseService $discourseService)
+    {
+        $this->discourseService = $discourseService;
+    }
+
+    private function getHost($idevents) {
+        $hosts = User::join('events_users', 'events_users.user', '=', 'users.id')
+            ->where('events_users.event', $idevents)
+            ->where('events_users.role', Role::HOST)
+            ->select('users.*')
+            ->get();
+
+        return $hosts->count() ? $hosts[0] : null;
+    }
+
+    public function handle(UserLeftEvent $e) {
+        if ($e->iduser) {
+            $event = Party::find($e->idevents);
+            $user = User::find($e->iduser);
+
+            // Might not exist - timing windows.
+            if ($event && $user && $event->discourse_thread) {
+                // We need a host of the event to add the user to the thread.
+                $host = $this->getHost($event->idevents);
+
+                if ($host) {
+                    $this->discourseService->removeUserFromPrivateMessage(
+                        $event->discourse_thread,
+                        $host->username,
+                        $user->username
+                    );
+                }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/app/Observers/EventsUsersObserver.php b/app/Observers/EventsUsersObserver.php
new file mode 100644
index 0000000000..1e15ca3efd
--- /dev/null
+++ b/app/Observers/EventsUsersObserver.php
@@ -0,0 +1,108 @@
+<?php
+
+namespace App\Observers;
+
+use App\Events\UserConfirmedEvent;
+use App\Events\UserLeftEvent;
+use App\EventsUsers;
+use App\Role;
+use App\Services\DiscourseService;
+use App\User;
+
+/**
+ * This class triggers add/removes from the Discourse thread when a user joins/leaves an event.
+ * It also maintains the count of volunteers for the event.
+ *
+ * Class EventsUsersObserver
+ * @package App\Observers
+ */
+class EventsUsersObserver {
+    private $discourseService;
+
+    public function __construct(DiscourseService $discourseService)
+    {
+        $this->discourseService = $discourseService;
+    }
+
+        /**
+     * Listen to the created event.
+     *
+     * @param  \App\EventsUsers  $eu
+     * @return void
+     */
+    public function created(EventsUsers $eu)
+    {
+        $idevents = $eu->event;
+        $event = \App\Party::find($idevents);
+        $iduser = $eu->user;
+        $user = $iduser ? User::find($iduser) : null;
+        
+        if ($eu->status == 1) {
+            // Confirmed.  Make sure they are on the thread.
+            $this->confirmed($event, $user);
+        } else {
+            // Not confirmed.  Make sure they are not on the thread.
+            $this->removed($event, $user);
+        }
+    }
+
+    /**
+     * Listen to the updated event.
+     *
+     * @param  \App\EventsUsers  $eu
+     * @return void
+     */
+    public function updated(EventsUsers $eu) {
+        $idevents = $eu->event;
+        $event = \App\Party::find($idevents);
+        $iduser = $eu->user;
+        $user = $iduser ? User::find($iduser) : null;
+
+        if ($eu->status == 1) {
+            // Confirmed.  Make sure they are on the thread.
+            $this->confirmed($event, $user);
+        } else {
+            // Not confirmed.  Make sure they are not on the thread.
+            $this->removed($event, $user);
+        }
+    }
+
+    /**
+     * Listen to the deleted event.
+     *
+     * @param  \App\EventsUsers  $eu
+     * @return void
+     */
+    public function deleted(EventsUsers $eu)
+    {
+        $idevents = $eu->event;
+        $event = \App\Party::find($idevents);
+        $iduser = $eu->user;
+        $user = $iduser ? User::find($iduser) : null;
+
+        // Make sure they are not on the thread.
+        $this->removed($event, $user);
+    }
+
+    /**
+     * @param Party $event
+     * @param User $user
+     * @return void
+     */
+    private function confirmed($event, $user): void
+    {
+        $event->increment('volunteers');
+        event(new UserConfirmedEvent($event->idevents, $user ? $user->id : null));
+    }
+
+    /**
+     * @param Party $event
+     * @param User $user
+     * @return void
+     */
+    private function removed($event, $user): void
+    {
+        $event->decrement('volunteers');
+        event(new UserLeftEvent($event->idevents, $user ? $user->id : null));
+    }
+}
diff --git a/app/Providers/AppServiceProvider.php b/app/Providers/AppServiceProvider.php
index ae260b2643..2c73288359 100644
--- a/app/Providers/AppServiceProvider.php
+++ b/app/Providers/AppServiceProvider.php
@@ -2,8 +2,10 @@
 
 namespace App\Providers;
 
+use App\EventsUsers;
 use App\Helpers\Geocoder;
 use App\Helpers\RobustTranslator;
+use App\Observers\EventsUsersObserver;
 use Auth;
 use Cache;
 use Illuminate\Support\ServiceProvider;
@@ -36,6 +38,8 @@ public function boot()
         });
 
         \Illuminate\Pagination\Paginator::useBootstrapThree();
+
+        EventsUsers::observe(EventsUsersObserver::class);
     }
 
     /**
diff --git a/app/Providers/EventServiceProvider.php b/app/Providers/EventServiceProvider.php
index 3f9788ea88..74df5d645d 100644
--- a/app/Providers/EventServiceProvider.php
+++ b/app/Providers/EventServiceProvider.php
@@ -5,13 +5,17 @@
 use App\Events\DeviceCreatedOrUpdated;
 use App\Events\EventDeleted;
 use App\Events\EventImagesUploaded;
+use App\Events\UserConfirmedEvent;
 use App\Events\UserDeleted;
 use App\Events\UserEmailUpdated;
 use App\Events\UserFollowedGroup;
 use App\Events\UserLanguageUpdated;
+use App\Events\UserLeftEvent;
 use App\Events\UserRegistered;
 use App\Events\UserUpdated;
 use App\Listeners\AddUserToDiscourseGroup;
+use App\Listeners\AddUserToDiscourseThreadForEvent;
+use App\Listeners\RemoveUserFromDiscourseThreadForEvent;
 use App\Listeners\AnonymiseSoftDeletedUser;
 use App\Listeners\DeleteEventFromWordPress;
 use App\Listeners\DeviceUpdatedAt;
@@ -87,6 +91,14 @@ class EventServiceProvider extends ServiceProvider
         DeviceCreatedOrUpdated::class => [
             DeviceUpdatedAt::class,
         ],
+
+        UserConfirmedEvent::class => [
+            AddUserToDiscourseThreadForEvent::class
+        ],
+
+        UserLeftEvent::class => [
+            RemoveUserFromDiscourseThreadForEvent::class
+        ]
     ];
 
     /**
diff --git a/app/Services/DiscourseService.php b/app/Services/DiscourseService.php
index a25c4bdfb6..b5f47e97fd 100644
--- a/app/Services/DiscourseService.php
+++ b/app/Services/DiscourseService.php
@@ -136,6 +136,40 @@ public function addUserToPrivateMessage($threadid, $addBy, $addUser)
         }
     }
 
+    public function removeUserFromPrivateMessage($threadid, $removeBy, $removeUser) {
+        if (! config('restarters.features.discourse_integration')) {
+            return;
+        }
+
+        Log::info("Remove user from private message $threadid, $removeBy, $removeUser");
+
+        $client = app('discourse-client', [
+            'username' => $removeBy,
+        ]);
+
+        $params = [
+            'username' => $removeUser,
+        ];
+
+        $endpoint = "/t/$threadid/remove-allowed-user";
+
+        Log::info('Removing from private message: '.json_encode($params));
+        $response = $client->request(
+            'PUT',
+            $endpoint,
+            [
+                'form_params' => $params,
+            ]
+        );
+
+        Log::info('Response status: '.$response->getStatusCode());
+        Log::info('Response body: '.$response->getBody());
+
+        if (! $response->getStatusCode() === 200) {
+            Log::error("Could not remove from private message ($threadid, $removeBy, $removeUser:".$response->getReasonPhrase());
+        }
+    }
+
     public function getAllUsers()
     {
         if (! config('restarters.features.discourse_integration')) {
diff --git a/tests/Feature/Events/AddRemoveVolunteerTest.php b/tests/Feature/Events/AddRemoveVolunteerTest.php
index 5a047e91bd..558a108d6c 100644
--- a/tests/Feature/Events/AddRemoveVolunteerTest.php
+++ b/tests/Feature/Events/AddRemoveVolunteerTest.php
@@ -4,7 +4,9 @@
 
 use App\EventsUsers;
 use App\Group;
+use App\Helpers\Fixometer;
 use App\Helpers\Geocoder;
+use App\Listeners\RemoveUserFromDiscourseThreadForEvent;
 use App\Network;
 use App\Notifications\AdminModerationEvent;
 use App\Notifications\NotifyRestartersOfNewEvent;
@@ -16,6 +18,7 @@
 use Illuminate\Support\Facades\Notification;
 use Symfony\Component\DomCrawler\Crawler;
 use Tests\TestCase;
+use Illuminate\Support\Facades\Queue;
 
 class AddRemoveVolunteerTest extends TestCase
 {
@@ -23,9 +26,10 @@ class AddRemoveVolunteerTest extends TestCase
      * @dataProvider roleProvider
      */
 
-    public function testAddRemove($role)
+    public function testAddRemove($role, $addrole, $shouldBeHost)
     {
         $this->withoutExceptionHandling();
+        Queue::fake();
 
         $group = Group::factory()->create();
         $network = Network::factory()->create();
@@ -53,7 +57,28 @@ public function testAddRemove($role)
 
         $this->actingAs($host);
 
-        $restarter = User::factory()->restarter()->create();
+        switch ($addrole) {
+            case 'Administrator':
+                $restarter = User::factory()->administrator()->create();
+                break;
+            case 'NetworkCoordinator':
+                $restarter = User::factory()->networkCoordinator()->create();
+                break;
+            case 'HostThis':
+                $restarter = User::factory()->host()->create();
+                $group->addVolunteer($restarter);
+                $group->makeMemberAHost($restarter);
+                break;
+            case 'HostOther':
+                $restarter = User::factory()->host()->create();
+                $group2 = Group::factory()->create();
+                $group2->addVolunteer($restarter);
+                $group2->makeMemberAHost($restarter);
+                break;
+            case 'Restarter':
+                $restarter = User::factory()->restarter()->create();
+        }
+
 
         // Add an existing user
         $response = $this->put('/api/events/' . $event->idevents . '/volunteers', [
@@ -79,6 +104,15 @@ public function testAddRemove($role)
             ]
         ]);
 
+        // Check they are/are not a host.
+        $hostFor = Party::hostFor([$restarter->id])->get();
+
+        if ($shouldBeHost) {
+            $this->assertTrue($hostFor->contains($event));
+        } else {
+            $this->assertFalse($hostFor->contains($event));
+        }
+
         // Remove them
         $volunteer = EventsUsers::where('user', $restarter->id)->first();
         $this->post('/party/remove-volunteer/', [
@@ -97,6 +131,12 @@ public function testAddRemove($role)
                                   ]
                               ]);
 
+        Queue::assertPushed(\Illuminate\Events\CallQueuedListener::class, function ($job) use ($event, $restarter) {
+            if ($job->class == RemoveUserFromDiscourseThreadForEvent::class) {
+                return true;
+            }
+        });
+
         // Add an invited user
         $restarter = User::factory()->restarter()->create();
         $response = $this->post('/party/invite', [
@@ -154,8 +194,10 @@ public function testAddRemove($role)
 
     public function roleProvider() {
         return [
-            [ 'Administrator' ],
-            [ 'NetworkCoordinator' ],
+            [ 'Administrator', 'Restarter', false ],
+            [ 'NetworkCoordinator', 'HostThis', true ],
+            [ 'NetworkCoordinator', 'HostOther', false ],
+            [ 'NetworkCoordinator', 'Administrator', false ],
         ];
     }
 
diff --git a/tests/Feature/Events/CreateEventTest.php b/tests/Feature/Events/CreateEventTest.php
index b291fab64c..7f897d59f2 100644
--- a/tests/Feature/Events/CreateEventTest.php
+++ b/tests/Feature/Events/CreateEventTest.php
@@ -2,15 +2,20 @@
 
 namespace Tests\Feature;
 
+use App\Events\UserConfirmedEvent;
+use App\Events\UserLeftEvent;
 use App\EventsUsers;
 use App\Group;
 use App\Helpers\Geocoder;
 use App\Helpers\RepairNetworkService;
+use App\Listeners\AddUserToDiscourseThreadForEvent;
+use App\Listeners\RemoveUserFromDiscourseThreadForEvent;
 use App\Network;
 use App\Notifications\AdminModerationEvent;
 use App\Notifications\NotifyRestartersOfNewEvent;
 use App\Party;
 use App\Role;
+use App\Services\DiscourseService;
 use App\User;
 use Carbon\Carbon;
 use DB;
@@ -453,13 +458,17 @@ public function emails_sent_to_coordinators_when_event_created()
     public function a_host_can_be_added_later()
     {
         $this->withoutExceptionHandling();
+        Queue::fake();
 
         $host = User::factory()->host()->create();
+        $host2 = User::factory()->host()->create();
         $this->actingAs($host);
 
         $group = Group::factory()->create();
         $group->addVolunteer($host);
         $group->makeMemberAHost($host);
+        $group->addVolunteer($host2);
+        $group->makeMemberAHost($host2);
 
         // Create the event
         $eventAttributes = Party::factory()->raw(['group' => $group->idgroups, 'event_date' => '2000-01-01', 'approved' => true]);
@@ -469,12 +478,27 @@ public function a_host_can_be_added_later()
         // Find the event id
         $party = $group->parties()->latest()->first();
 
+        // Add the second host.
+        $response = $this->put('/api/events/' . $party->idevents . '/volunteers?api_token=' . $host->api_token, [
+            'volunteer_email_address' => $host2->email,
+            'full_name' => $host2->name,
+            'user' => $host2->id,
+        ]);
+
+        $response->assertSuccessful();
+
         // Remove the host from the event
         $volunteer = EventsUsers::where('user', $host->id)->first();
         $this->post('/party/remove-volunteer/', [
             'id' => $volunteer->idevents_users,
         ])->assertSee('true');
 
+        Queue::assertPushed(\Illuminate\Events\CallQueuedListener::class, function ($job) use ($party, $host) {
+            if ($job->class == RemoveUserFromDiscourseThreadForEvent::class) {
+                return true;
+            }
+        });
+
         // Assert that we see the host in the list of volunteers to add to the event.
         $response = $this->get('/api/groups/'. $group->idgroups . '/volunteers?api_token=' . $host->api_token);
         $response->assertJson([
@@ -486,7 +510,10 @@ public function a_host_can_be_added_later()
         ]);
 
         // Assert we can add them back in.
-        $response = $this->put('/api/events/' . $party->idevents . '/volunteers', [
+        $party->discourse_thread = 123;
+        $party->save();
+
+        $response = $this->put('/api/events/' . $party->idevents . '/volunteers?api_token=' . $host->api_token, [
             'volunteer_email_address' => $host->email,
             'full_name' => $host->name,
             'user' => $host->id,
@@ -495,6 +522,30 @@ public function a_host_can_be_added_later()
         $response->assertSuccessful();
         $rsp = json_decode($response->getContent(), TRUE);
         $this->assertEquals('success', $rsp['success']);
+
+        // Check the listener was queued to be called in the background.
+        Queue::assertPushed(\Illuminate\Events\CallQueuedListener::class, function ($job) use ($party, $host) {
+            if ($job->class == AddUserToDiscourseThreadForEvent::class) {
+                return true;
+            }
+        });
+
+        // Manually call the listener for coverage and check it calls through to Discourse.
+        $this->instance(
+            DiscourseService::class,
+            \Mockery::mock(DiscourseService::class, function ($mock) {
+                $mock->shouldReceive('addUserToPrivateMessage')->once();
+                $mock->shouldReceive('removeUserFromPrivateMessage')->once();
+            })
+        );
+
+        $listener = app()->make(AddUserToDiscourseThreadForEvent::class);
+        $event = new UserConfirmedEvent($party->idevents, $host->id);
+        $listener->handle($event);
+
+        $listener = app()->make(RemoveUserFromDiscourseThreadForEvent::class);
+        $event = new UserLeftEvent($party->idevents, $host->id);
+        $listener->handle($event);
     }
 
     public function provider()
@@ -634,6 +685,8 @@ public function no_notification_after_leaving() {
     /** @test */
     public function notifications_are_queued_as_expected()
     {
+        Notification::fake();
+
         // At the moment we are queueing (backgrounding) admin notifications but not user notifications.
         //
         // Don't call Notification::fake() - we want real notifications.
@@ -641,6 +694,7 @@ public function notifications_are_queued_as_expected()
 
         // Create an admin
         $admin = User::factory()->administrator()->create();
+
         // Create a network with a group.
         $network = Network::factory()->create();
         $group = Group::factory()->create();
@@ -655,47 +709,23 @@ public function notifications_are_queued_as_expected()
         $group->makeMemberAHost($host);
         $this->actingAs($host);
 
-        // Clear any jobs queued in earlier tests.
-        $max = 1000;
-        do {
-            $job = Queue::pop('database');
-
-            if ($job) {
-                try {
-                    $job->fail('removed in UT');
-                } catch (\Exception $e) {}
-            }
-
-            $max--;
-        }
-        while (Queue::size() > 0 && $max > 0);
-
         // Create an event.
-        $initialQueueSize = \Illuminate\Support\Facades\Queue::size('database');
         $event = Party::factory()->raw();
         $event['group'] = $group->idgroups;
         $response = $this->post('/api/v2/events?api_token=' . $host->api_token, $this->eventAttributesToAPI($event));
         $response->assertSuccessful();
 
-        // Should have queued AdminModerationEvent.
-        $queueSize = Queue::size();
-        self::assertGreaterThan($initialQueueSize, $queueSize);
-
-        // Fail it.
-        $job = Queue::pop();
-        self::assertNotNull($job);
-        self::assertStringContainsString('AdminModerationEvent', $job->getRawBody());
-        try {
-            $job->fail('removed in UT');
-        } catch (\Exception $e) {}
-        self::assertEquals(0, Queue::size('database'));
+        Notification::assertSentTo(
+            [$admin], AdminModerationEvent::class
+        );
 
-        // Approval should generate a notification to the host which is also queued.
+        // Approval should generate a notification to the host.
         $event = Party::latest()->first();
         $event->approve();
 
-        # Should have queued ApproveEvent.
-        self::assertEquals(0, Queue::size('database'));
+        Notification::assertSentTo(
+            [$host], EventConfirmed::class
+        );
     }
 
     /** @test */
diff --git a/tests/Feature/Events/DeleteEventTest.php b/tests/Feature/Events/DeleteEventTest.php
index 17c8b243dc..71a1918fa1 100644
--- a/tests/Feature/Events/DeleteEventTest.php
+++ b/tests/Feature/Events/DeleteEventTest.php
@@ -61,7 +61,7 @@ public function an_admin_can_delete_an_event()
         $this->actingAs($admin);
         $response = $this->get("/api/group/{$group->idgroups}/stats?api_token=1234");
         $stats = json_decode($response->getContent(), true);
-        $this->assertEquals(9, $stats['num_hours_volunteered']);
+        $this->assertEquals(21, $stats['num_hours_volunteered']);
 
         // Now delete the event.
         $response = $this->post('/party/delete/'.$event->idevents);
diff --git a/tests/Feature/Events/EventRequestReviewEmailTest.php b/tests/Feature/Events/EventRequestReviewEmailTest.php
index cb42445d4b..8ce0e817c5 100644
--- a/tests/Feature/Events/EventRequestReviewEmailTest.php
+++ b/tests/Feature/Events/EventRequestReviewEmailTest.php
@@ -75,8 +75,6 @@ protected function init_event_and_dependencies()
             'full_name' => null,
         ]);
 
-        $this->event->increment('volunteers');
-
         $this->assertTrue($this->group->isVolunteer($this->volunteer->getKey()));
         $this->assertTrue($this->event->isVolunteer($this->volunteer->getKey()));
     }
diff --git a/tests/Feature/Events/ExportTest.php b/tests/Feature/Events/ExportTest.php
index 84fdac5e7d..5d53fc3ed2 100644
--- a/tests/Feature/Events/ExportTest.php
+++ b/tests/Feature/Events/ExportTest.php
@@ -76,6 +76,8 @@ public function testExport($role)
         $group3->approved = false;
         $group3->save();
 
+        $this->artisan("queue:work --stop-when-empty");
+
         $this->actingAs($user);
 
         // Create an event on each and approve it.
diff --git a/tests/Feature/Events/InviteEventTest.php b/tests/Feature/Events/InviteEventTest.php
index 390f5e18f1..5652443607 100644
--- a/tests/Feature/Events/InviteEventTest.php
+++ b/tests/Feature/Events/InviteEventTest.php
@@ -2,12 +2,10 @@
 
 namespace Tests\Feature;
 
-use App\Events\ApproveEvent;
 use App\EventsUsers;
 use App\Group;
 use App\Helpers\Fixometer;
-use App\Listeners\CreateDiscourseThreadForEvent;
-use App\Listeners\CreateWordpressPostForEvent;
+use App\Listeners\AddUserToDiscourseThreadForEvent;
 use App\Notifications\RSVPEvent;
 use App\Party;
 use App\Role;
@@ -17,6 +15,7 @@
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 use Tests\TestCase;
 use App\Notifications\JoinEvent;
+use Illuminate\Support\Facades\Queue;
 
 class InviteEventTest extends TestCase
 {
@@ -264,17 +263,26 @@ public function testInvitableUserPOV()
 
     public function testInvitableNotifications()
     {
+        Queue::fake();
         Notification::fake();
         $this->withoutExceptionHandling();
 
-        $group = Group::factory()->create();
+        $user = User::factory()->administrator()->create([
+            'api_token' => '1234',
+        ]);
+        $this->actingAs($user);
+
+        $idgroups = $this->createGroup('Test Group', 'https://therestartproject.org', 'London', 'Some text.', true, true);
+        $idevents = $this->createEvent($idgroups, 'tomorrow');
+
+        // Joining should trigger adding to the Discourse thread.  Fake one.
+        $event = \App\Party::find($idevents);
+        $event->discourse_thread = 123;
+        $event->save();
+
+        $group = Group::find($idgroups);
         $host = User::factory()->host()->create();
-        $event = Party::factory()->create([
-                                                   'group' => $group,
-                                                   'event_start_utc' => '2130-01-01T12:13:00+00:00',
-                                                   'event_end_utc' => '2130-01-01T13:14:00+00:00',
-                                                   'user_id' => $host->id
-                                               ]);
+        $event = Party::find($idevents);
         EventsUsers::create([
                                 'event' => $event->getKey(),
                                 'user' => $host->getKey(),
@@ -327,7 +335,7 @@ public function testInvitableNotifications()
         $this->get('/logout');
         $this->actingAs($user);
 
-        // Now accept the invitation.
+        // Now accept the invitation, which should trigger adding to the Discourse thread.
         $eu = EventsUsers::where('user', '=', $user->id)->first();
         $invitation = '/party/accept-invite/' . $event->idevents . '/' . $eu->status;
 
@@ -359,6 +367,12 @@ function ($notification, $channels, $host) use ($user, $event) {
         $response9 = $this->get('/party/get-group-emails-with-names/'.$event->idevents);
         $members = json_decode($response9->getContent());
         $this->assertEquals([], $members);
+
+        Queue::assertPushed(\Illuminate\Events\CallQueuedListener::class, function ($job) use ($event, $user) {
+            if ($job->class == AddUserToDiscourseThreadForEvent::class) {
+                return true;
+            }
+        });
     }
 
     public function testInviteViaLink() {
diff --git a/tests/Feature/Events/JoinEventTest.php b/tests/Feature/Events/JoinEventTest.php
index 6c32aa7b57..3787c884b9 100644
--- a/tests/Feature/Events/JoinEventTest.php
+++ b/tests/Feature/Events/JoinEventTest.php
@@ -2,13 +2,10 @@
 
 namespace Tests\Feature;
 
+use App\Listeners\RemoveUserFromDiscourseThreadForEvent;
+use Illuminate\Support\Facades\Queue;
 use App\EventsUsers;
-use App\Group;
-use App\Helpers\Geocoder;
-use App\Network;
-use App\Notifications\AdminModerationEvent;
-use App\Notifications\NotifyRestartersOfNewEvent;
-use App\Party;
+use App\Listeners\AddUserToDiscourseThreadForEvent;
 use App\User;
 use DB;
 use Illuminate\Support\Facades\Notification;
@@ -18,17 +15,32 @@ class JoinEventTest extends TestCase
 {
     public function testJoin()
     {
-        $this->withoutExceptionHandling();
+        Queue::fake();
 
-        $group = Group::factory()->create([
-                                              'approved' => true
-                                           ]);
-        $event = Party::factory()->create(['group' => $group->idgroups]);
+        $this->withoutExceptionHandling();
 
-        $user = User::factory()->restarter()->create();
+        $user = User::factory()->administrator()->create([
+            'api_token' => '1234',
+        ]);
         $this->actingAs($user);
 
+        $idgroups = $this->createGroup('Test Group', 'https://therestartproject.org', 'London', 'Some text.', true, true);
+        $idevents = $this->createEvent($idgroups, 'tomorrow');
+
+        // Joining should trigger adding to the Discourse thread.  Fake one.
+        $event = \App\Party::find($idevents);
+        $event->discourse_thread = 123;
+        $event->save();
+
+        Queue::assertPushed(\Illuminate\Events\CallQueuedListener::class, function ($job) use ($event, $user) {
+            if ($job->class == AddUserToDiscourseThreadForEvent::class) {
+                return true;
+            }
+        });
+
         // Join.  Should get redirected, and also prompted to follow the group (which we haven't).
+        $user = User::factory()->restarter()->create();
+        $this->actingAs($user);
         $response = $this->get('/party/join/'.$event->idevents);
         $this->assertTrue($response->isRedirection());
         $response->assertSessionHas('prompt-follow-group');
@@ -53,6 +65,12 @@ public function testJoin()
                 ':is-attending' => 'false',
             ],
         ]);
+
+        Queue::assertPushed(\Illuminate\Events\CallQueuedListener::class, function ($job) use ($event, $user) {
+            if ($job->class == RemoveUserFromDiscourseThreadForEvent::class) {
+                return true;
+            }
+        });
     }
 
     public function testJoinInvalid() {
diff --git a/tests/Feature/Events/ModerationEventPhotosNotificationTest.php b/tests/Feature/Events/ModerationEventPhotosNotificationTest.php
index 3fa6c1b0e4..dfe59d32d6 100644
--- a/tests/Feature/Events/ModerationEventPhotosNotificationTest.php
+++ b/tests/Feature/Events/ModerationEventPhotosNotificationTest.php
@@ -131,8 +131,6 @@ protected function init_event_and_dependencies()
             'full_name' => null,
         ]);
 
-        $this->event->increment('volunteers');
-
         $this->assertTrue($this->group->isVolunteer($this->restarter->getKey()));
         $this->assertTrue($this->event->isVolunteer($this->restarter->getKey()));
     }
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 4712dcdc49..8421d208ed 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -118,6 +118,20 @@ protected function setUp(): void
         $this->processQueuedNotifications();
         $this->OpenAPIValidator = ValidatorBuilder::fromJson(storage_path('api-docs/api-docs.json'))->getValidator();
 
+        // Clear any jobs queued in earlier tests.
+        $max = 1000;
+        do {
+            $job = Queue::pop('database');
+
+            if ($job) {
+                try {
+                    $job->fail('removed in UT');
+                } catch (\Exception $e) {}
+            }
+
+            $max--;
+        }
+        while (Queue::size() > 0 && $max > 0);
     }
 
     public function userAttributes()