```ruby
class Mailboxer::AttachmentUploader < CarrierWave::Uploader::Base
  storage :fog

  def store_dir
    "public/messages/#{model.id}/attachment"
  end

  def extension_white_list
    %w(jpg jpeg png pdf)
  end
end
```

Remove attachment file extension restrick
user
```ruby
class Mailboxer::AttachmentUploader < CarrierWave::Uploader::Base
  storage :fog

  def store_dir
    "public/messages/#{model.id}/attachment"
  end

  # def extension_white_list
  #   %w(jpg jpeg png pdf)
  # end
end
```
assistant