app.php

<?php

// application\bootstrap\app.php

Core::bind('\Concrete\Core\Workflow\BasicWorkflow', function() {
    return new \Application\Src\Workflow\BasicWorkflow();
});

BasicWorkflow.php

<?php
namespace Application\Src\Workflow;

use Concrete\Core\Workflow\Progress\Progress as WorkflowProgress;
use Core;
use PermissionKey;

class BasicWorkflow extends \Concrete\Core\Workflow\BasicWorkflow
{
    protected function notify(
        WorkflowProgress $wp,
        $message,
        $permission = 'notify_on_basic_workflow_entry',
        $parameters = array()
    )
    {
        $nk = PermissionKey::getByHandle($permission);
        $nk->setPermissionObject($this);
        $users = $nk->getCurrentlyActiveUsers($wp);

        foreach ($users as $ui) {
            $mh = Core::make('helper/mail');
            $mh->addParameter('uName', $ui->getUserName());
            $mh->to($ui->getUserEmail());
            $mh->from('example@example.com', t('Basic Workflow'));
            $mh->addParameter('message', $message);
            foreach ($parameters as $key => $value) {
                $mh->addParameter($key, $value);
            }
            $mh->addParameter('siteName', Core::make('config')->get('concrete.site'));
            $mh->load('basic_workflow_notification');
            $mh->sendMail();
            unset($mh);
        }
    }

}