function send_activation_link($user, $email, $password, $key)
 {
     require_once WPPR_PLUGIN_DIR . '/models/signup-model.php';
     $model = new Signup_Model();
     $template = $model->get_message_template(1);
     $subject = $template->message_subject;
     $message = $template->message_body;
     $home_url = home_url('confirm');
     $confirmation_link = add_query_arg(array('key' => $key, 'user' => $user), $home_url);
     $placeholders = array('USERNAME' => $user, 'CONFIRM_LINK' => $confirmation_link, 'PASSWORD' => $password);
     foreach ($placeholders as $key => $value) {
         $message = str_replace('{' . $key . '}', $value, $message);
     }
     $headers = 'From: noreply@pinoyrunners.co' . "\r\n";
     wp_mail($email, $subject, $message, $headers);
 }