mime
这有个例子：
/*
*  class mime_mail
*  original implementation by sascha schumann
*  modified by tobias ratschiller :
*      - general code clean-up
*      - separate body- and from-property
*      - killed some mostly un-necessary stuff
*/
class mime_mail
{
var $parts;
var $to;
var $from;
var $headers;
var $subject;
var $body;
/*
  *     void mime_mail()
  *     class constructor
  */
function mime_mail()
  {
  $this->parts = array();
  $this->to = ;
  $this->from = ;
  $this->subject = ;
  $this->body = ;
  $this->headers = ;
  }
/*
  *     void add_attachment(string message, [string name], [string ctype])
  *     add an attachment to the mail object
  */
function add_attachment($message, $name = , $ctype =
application/octet-stream)
  {
  $this->parts[] = array (
                          ctype => $ctype,
                          message => $message,
                          encode => $encode,
                          name => $name
                          );
  }
/*
*      void build_message(array part=
*      build message parts of an multipart mail
*/
function build_message($part)
{
$message = $part[message];
$message = chunk_split(base64_encode($message));
$encoding = base64;
return content-type: .$part[ctype].
                        ($part[name]?; name=\.$part[name].\:).
                        \ncontent-transfer-encoding: $encoding.
            \ncontent-disposition: inline.
            ($part[name]?; filename=\.$part[name].\:).
            \n\n$message\n;
}
/*
*      void build_multipart()
*      build a multipart mail
*/
function build_multipart()
{
$boundary = b.md5(uniqid(time()));
$multipart = content-type: multipart/mixed; boundary = \$boundary\\n\nthis
is a mime encoded message.\n\n--$boundary;
for($i = sizeof($this->parts)-1; $i >= 0; $i--)
    {
    $multipart .= \n.$this->build_message($this->parts[$i]).--$boundary;
    }
return $multipart.= --\n;
}
/*
*      void send()
*      send the mail (last class-function to be called)
*/
function send()
{
$mime = ;
if (!empty($this->from))
    $mime .= from: .$this->from.\n;
if (!empty($this->headers))
    $mime .= $this->headers.\n;
if (!empty($this->body))
    $this->add_attachment($this->body, , text/plain);
$mime .= mime-version: 1.0\n.$this->build_multipart();
mail($this->to, $this->subject, , $mime);
}
}; // end of class
/*
* example usage
*
$attachment = fread(fopen(test.jpg, r), filesize(test.jpg));
$mail = new mime_mail();
$mail->from = foo@bar.com;
$mail->headers = errors-to: foo@bar.com;
$mail->to = bar@foo.com;
$mail->subject = testing...;
$mail->body = this is just a test.;
$mail->add_attachment($attachment, test.jpg, image/jpeg);
$mail->send();
*/
?>