I have since changed the header to: $rtf_filename = "root_cause-$daterange.rtf"; print ("Content-type: application/rtf\n"); print ("Content-Disposition: attachment; filename=$rtf_filename\n"); $h = RTF::Writer->new_to_handle(*STDOUT); $h->prolog( 'title' => "Greetings, hyoomon" ); $h->number_pages; $h->paragraph(\'\fs40\b\i', "Hi there!"); $h->close; I still malformed headers with this error: malformed header: {\rtfi\ansi\deff0{\fonttbl