Laravel 5.1 Event Listener that prevents emails from being sent to email addresses that have bounced previously.

AppServiceProvider.php

<?php

// Filter Emails in the Bounce List
Event::listen('mailer.sending',function(\Swift_Message $swiftype_message){

    // Get the Original Recipients of the Mail
    $recipients = $swiftype_message->getTo();
    // Log::info('Original Recepients: '.json_encode($recipients));

    // Check if Any of the Email Addresses are in the Problem Emails Database
    $email_addresses = array_keys($recipients);
    $problem_emails = ProblemEmail::whereIn('email_address',$email_addresses)->get();
    // Log::info('Problem Emails: '.json_encode($problem_emails));

    // Remove all the Problem Emails from the Recipients List
    foreach($problem_emails as $problem_email){
        unset($recipients[$problem_email->email_address]);
    }

    // Log::info('Final Emails: '.json_encode($recipients));

    // Set the Recipients List Once Again
    // If the Number of recipients is less than 1, send a pretend mail
    // We do this, because sending a mail to 0 recipients throws an error
    if(count($recipients) > 0){
        $swiftype_message->setTo($recipients);
    }else{
        Mail::pretend();
    }

});