Spam Assassin is a program that runs on TH Media's mail servers. It examines each incoming message and computes a "SPAM score" based on a wide range of different criteria. If the score is high enough, it adds a special flag to the headers of the message that you can use to identify it as probable unsolicited commercial e-mail. When your e-mail server receive a message, Spam Assassin compares the message to its database of different SPAM criteria. Spam Assassin produces a numerical score based on those criteria. If the score is higher than a threshold value, Spam Assassin adds headers to the e-mail to track spam. You can also have it change the subject line (***SPAM***) and use your local filters to filter out spam. Within your Cpanel, you can control whether or not Spam Assassin scans your mail, and if so, you can assign different values to help filter spam.