When you package content with an emfield field into a feature and export it, you will get the error when visiting the node form.

"The selected file /tmp/fileC0zUk9 could not be uploaded, because the destination is not properly configured. Thumbnail error. Could not copy provider thumbnail."

This is because the user never visited/saved the field form and emthumb_form_check_directory() was never called.

You have to have a clean files directory and a clean drupal install. You also must set emimport_image_path.