CAMELOT Security is a server side based spam filtering solution for MS Windows platforms. Incoming messages run through a chain of different application layers inside a multi-tier protection system. Several methods of analysis are executed by active content processors, using artificial intelligence with self-learning filter processes. A special SMTP gateway verifies the identity of the sending instance and denies all further processing as soon as an invalid incident occurs. This prevents unauthorized access before the message is delivered to the regular mail system.