Wordpress Code To Allow Upload Of Microsoft Publisher Files

I need you to write some php code to allow a wordpress site to upload Microsoft Publisher Files. I have tried this but it doesn't work and get this error message on upload (“Test doc for [login to view URL]” has failed to upload. Sorry, this file type is not permitted for security reasons.) //The code I have tried add_filter('upload_mimes', 'add_custom_upload_mimes'); function add_custom_upload_mimes( $existing_mimes ){ //PUBLISHER FILES - ISSUE //$existing_mimes['pub'] = 'application/vnd.ms-publisher'; //$existing_mimes['pub'] = 'application/mspublisher'; // neither of the above works for me return $existing_mimes; } Please note you will need to develop and test this in your own wordpress environment. I have provided a sample Microsoft Publisher file for you to try and upload.