Walys I have the same problem. I prefer to disable all the email notification as well.
Then I found the way someone has tired to revise it to disable the default setting of email notification of the private disscusion extension:
`
use Flarum\User\Event\Registered;
use Flarum\User\User;
use Illuminate\Events\Dispatcher;
return [
function (Dispatcher $events) {
$events->listen(Registered::class, function (Registered $event) {
foreach (['post', 'user'] as $key)
foreach (['byobuPrivateDiscussionCreated','byobuPrivateDiscussionAdded','byobuRecipientRemoved','byobuPrivateDiscussionReplied'] as $key2){
$event->user->setPreference(
User::getNotificationPreferenceKey("{$key}Mentioned", 'email'),
true
);
$event->user->setPreference(
User::getNotificationPreferenceKey("{$key2}", 'email'),
false
);
}
$event->user->setPreference('followAfterReply', false);
$event->user->save();
});
},
];`
