A workaround could be to replace the feedback form with a custom object with a file field. Then, the visitor should actually publish new objects of this type through the form, and the administrator is notified of the new publication by an email (see the simple notification extension in the contribs).
Files in feed back forms: http://ez.no/developer/contribs/datatypes/enhanced_ezbinaryfile
Didn't find the extension though, might be one of these:
http://ez.no/developer/contribs/workflow/sck_cen_create_subtree_notification_rule http://ez.no/developer/contribs/workflow/subtree_notification_workflow_event