用PHP3发送MIME格式的邮件

这有个例子：

/*
*  Class mime_mail
*  Original implementation by Sascha Schumann <sascha@schumann.cx>
*  Modified by Tobias Ratschiller <tobias@dnet.it>:
*      - 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();

*/
?>