As soon as new methods are introduced, spammers find ways to circumvent them. This is how the most effective software works. The first method is called blacklisting. Blacklisting works by identifying the IP address of the sender's computer and then blocking communication with that IP. The second method is filtering. Bayesian filtering is the most popular filtering method. It works by analyzing which mail you read and which you don't. It is then able to learn over time which mail you want and which mail you do not want. The third method is called profiling. This scans the message for telltale signs of spam such as pattern, keywords, invalid message IDs, and bugs. A score is then assigned to the message. If the score exceeds a certain threshold, the message is rejected. The last method is simply called labeling. In most states, senders are required to mark their messages as spam or legitimate mail. This allows the user to choose whether or not they want to see