/**
 * Füge weitere Mime Types für den Download der Produkte hinzu
 */
function add_custom_mime_types($mimes){

 $new_file_types = array (
 'zip' => 'application/zip',
 'mobi' => 'application/x-mobipocket-ebook',
 'pdf' => 'application/pdf',
 'epub' => 'application/epub+zip'
 );

 return array_merge($mimes,$new_file_types);
}
add_filter('upload_mimes','add_custom_mime_types');