diff --git a/fillpdf.rules_defaults.inc b/fillpdf.rules_defaults.inc
index ea6666a42ff58083008b9514210837bacb779f45..8eebe7936542148cd5f45746dab4a2a16c62bb8e 100644
--- a/fillpdf.rules_defaults.inc
+++ b/fillpdf.rules_defaults.inc
@@ -37,6 +37,7 @@ function fillpdf_default_rules_configuration() {
             }
           },
           { "mimemail" : {
+              "key" : "send-pdf-as-attachment",
               "to" : [ "site:mail" ],
               "subject" : "Copy of completed PDF for your records",
               "body" : "Thank you for filling out the form on our website. A copy of your completed PDF is attached.",