[RaZEr]

function send($server, $to, $from, $subject="", $headers="") { 

    $headers="To: $to\nFrom: $from\nSubject: $subject\nX-Mailer: The Mouse!\n$headers";
    $fp = fsockopen($server, 25, &$errno, &$errstr, 30);
    if (!$fp)
       die("Server $server. Connection failed: $errno, $errstr");
    fputs($fp,"HELO $server\n");
    fputs($fp,"MAIL FROM: $from\n");
    fputs($fp,"RCPT TO: $to\n");
    fputs($fp,"DATA\n");
    fputs($fp,$this->headers);
    if (strlen($headers))
      fputs($fp,"$headers\n");
    fputs($fp,$this->mime);
    fputs($fp,"\n.\nQUIT\n");
    while(!feof($fp))
      $resp.=fgets($fp,1024);
    fclose($fp);
  }

PS: не проверял.