webmaster e-mail notification problem

My guestbook works fine except for one thing. When I receive an email notification that someone has signed, their address looks like this. nobody@pD954AFB1.dip.t-dialin.net [test]. I would like it to show up with their email address. I saw a post that told me I had to change this portion of add.class.php, but the portion between lines 225 and 236 looked the same as the post that I was reading.

if ($this->db->VARS["notify_guest"]==1 && $this->email != '') {
@mail($this->email,$this->db->LANG["EmailGuestSubject"],$this->db->VARS["notify_mes"], "From: <".$this->db->VARS['admin_mail']."> ".$this->db->VARS['admin_mail']."\nX-Mailer: Advanced Guestbook 2");

Can anyone help please.