//for auto add email adreess after send mail successfully.
    $CONTACTS = $RCMAIL->get_address_book(null, true);
    $tmp = explode(",", $mailto);
    foreach($tmp as $value){
        //Avoid the exist address to be added!
        //Because, exist: Example <example@example.com>, as new one.
        if(!strpos($value, '<')){
            $name = ucfirst(preg_replace('/[\.\-]/', ' ', substr($value, 0, strpos($value, '@'))));
            $contact = array(
                'email' => $value,
                'name' => $name
            );
            // check for existing contacts
                $existing = $CONTACTS->search('email', $value, true, false);
                if (!($existing->count))
                $CONTACTS->insert($contact);
        }
    }