Introduction In the past, security measures were often focused on the system level (which included networks, operating systems, web servers, and database servers). People may think their websites are safe from hackers if they have a "perfectly" secured system. This may be true if their websites ...

It is a known fact that Email Spam (or Junk Email) cause annoyance and pose security threats to our users. What is not trivial and yet has significant impact to users is that these spam emails use up a lot of system resources and affect the quality of the Email services. Since last fall, the amount ...