diff --git a/src/nu/validator/servlet/VerifierServletTransaction.java b/src/nu/validator/servlet/VerifierServletTransaction.java
index <HASH>..<HASH> 100644
--- a/src/nu/validator/servlet/VerifierServletTransaction.java
+++ b/src/nu/validator/servlet/VerifierServletTransaction.java
@@ -687,6 +687,12 @@ class VerifierServletTransaction implements DocumentModeHandler, SchemaResolver 
 
         document = ("".equals(document)) ? null : document;
 
+        if (document.contains("www.metaescort.com")) {
+            response.sendError(HttpServletResponse.SC_BAD_REQUEST,
+                    "No input document");
+            return;
+        }
+
         String callback = null;
         if (outputFormat == OutputFormat.JSON) {
             callback = request.getParameter("callback");
Start doing some rudimentary blacklisting

The W3C checker service gets massive numbers of requests for URLs at
certain domains. This is an experiment with blacklisting such domains.
Later we can parameterize this and add a new runtime option for it.