Tools\Mailer\Email::_getMimeByExtension PHP Method

    protected function _getMimeByExtension($ext, $default = 'application/octet-stream')
    {
        if (!isset($this->_Mime)) {
            $this->_Mime = new Mime();
        }
        $mime = $this->_Mime->getMimeTypeByAlias($ext);
        if (!$mime) {
            $mime = $default;
        }
        return $mime;
    }