diff --git a/booking.emails_admin.inc b/booking.emails_admin.inc
index f34e364..d573456 100644
--- a/booking.emails_admin.inc
+++ b/booking.emails_admin.inc
@@ -285,7 +285,11 @@ function booking_emails_custom_ajax_form($node, &$form_state) {
     $emailtype = $form_state['input']['email-type'];
     $subject_value = $form_state['input']['booking_email_subjectline_custom'];
     $body_value = $form_state['input']['booking_email_body_custom']['value'];
-    $submit_button_disabled = FALSE;
+
+    // only enable the submit button if the email type is not the initial empty one
+    if ($form_state['input']['email-type'] !== 'NULL') {
+      $submit_button_disabled = FALSE;
+    }
   }  
 
   if(variable_get('booking_enable_html_mail', 0) == 1) {