diff --git a/proxy/file.php b/proxy/file.php
index 946d32f..5c1c6ce 100644
--- a/proxy/file.php
+++ b/proxy/file.php
@@ -10,6 +10,8 @@
 require_once "config.php";
 require_once "proxy.php";
 
+if (!$target_file) civiproxy_http_error("Feature disabled", 405);
+
 // basic check
 civiproxy_security_check('file');
 
diff --git a/proxy/open.php b/proxy/open.php
index 0c9501b..9ed172a 100644
--- a/proxy/open.php
+++ b/proxy/open.php
@@ -10,6 +10,10 @@
 require_once "config.php";
 require_once "proxy.php";
 
+// see if mail open tracking is enabled
+if (!$target_open) civiproxy_http_error("Feature disabled", 405);
+
+
 // basic check
 civiproxy_security_check('open');
 
diff --git a/proxy/proxy.php b/proxy/proxy.php
index 93d33bc..100e509 100644
--- a/proxy/proxy.php
+++ b/proxy/proxy.php
@@ -160,6 +160,6 @@ function civiproxy_get_parameters($valid_parameters) {
  * and ends processing
  */
 function civiproxy_http_error($message, $code = 404) {
-  header("HTTP/1.1 $code $message");
+  header("HTTP/1.1 $code $message (CiviProxy $civiproxy_version)");
   exit();
 }
diff --git a/proxy/rest.php b/proxy/rest.php
index 2d588df..21bdc97 100644
--- a/proxy/rest.php
+++ b/proxy/rest.php
@@ -10,6 +10,9 @@
 require_once "config.php";
 require_once "proxy.php";
 
+// see if REST API is enabled
+if (!$target_rest) civiproxy_http_error("Feature disabled", 405);
+
 
 // basic check
 if (!civiproxy_security_check('rest')) {
diff --git a/proxy/url.php b/proxy/url.php
index e4fb355..a1ca659 100644
--- a/proxy/url.php
+++ b/proxy/url.php
@@ -10,6 +10,9 @@
 require_once "config.php";
 require_once "proxy.php";
 
+// see if URL tracking is enabled
+if (!$target_url) civiproxy_http_error("Feature disabled", 405);
+
 // basic check
 civiproxy_security_check('url');