Laravel Notifications - delay email sending and cancel if condition met

I have an app where I am sending a push notification which is fine if the user is logged into the application - however, if they're not / if they have not read the notification within X minutes I'd like to send them an email.

The way I am going about this is to use Laravel Notifications to create a mail, broadcast & database notification. On the toMail() method I'm returning a mailable with a delay -

public function toMail($notifiable)
{
    return (new \App\Mail\Order\NewOrder($this->order))
        ->delay(now()->addMinutes(10));
}

After the minutes are up, the email will send but, before the send goes ahead I'd like to perform a check to see if the push/database notification has already been marked as read and if it has cancel the email send. The only way I can think to do this is to bind to the MessageSending event that is baked into Laravel -

// listen for emails being sent
'Illuminate\Mail\Events\MessageSending' => [
    'App\Listeners\Notification\SendingEmail'
],

The only problem is this listener receives a Swift mail event and not the original mailable I was dispatching so I don't know how to cancel it. Any ideas and thanks in advance?

via Chebli Mohamed