expand php mail function to include smtp authentication..

Hi, I have a php mail function created by someone else, which works great.

I just want to add smtp authentication to this; how can I expand my function so that I could specify an smtp host, smtp authentication, an smtp username and pass?

thanks.

<?php
 
class simple_mail{
 var $to;
 var $from;  
 var $subject;
 var $body;
 var $html;
 
 function simple_mail(){  
  $this->to   = "";
  $this->from  = "";  
  $this->subject = "";
  $this->body  = "";
  $this->html  = 0;
 }
 
 function send(){
 
  if($this->html == 1)
  {
         $headers  = "MIME-Version: 1.0\r\n";
       $headers .= "Content-type: text/html; charset=iso-8859-1\r\n";
  }
 
  $headers .= "From: ".$this->from."\r\n";
 
  if(@mail($this->to, $this->subject, $this->body, $headers)!= 1)
            return false;
  else
   return true;
}
}
?>