Allow .oft file extension
To add mime types without hacking core files, you will want to create a new module and use the hook_file_mimetype_mappings_alter.
For example assuming you name your module oftmimetype then like this:

&lt;?php
/**
 * Implements hook_file_mimetype_mapping_alter().
 */
function oftmimetype_file_mimetype_mapping_alter(&amp;$mapping) {    
  // Add support for oft.
  $mime_type = 'application/x-font-otf';
  // If the mime type does not already exist, add it.
  if (!in_array($mime_type, $mapping['mimetypes'])) {
    $mapping['mimetypes'][] = $mime_type;
  }
  // Get the array index for that mime type and assign the extension to it.
  $mapping['extensions']['oft'] = array_search($mime_type, $mapping['mimetypes']);
  }
}
?&gt;