How Does Antispam Work?
Antispam contains several hundred spam tests that analyze individual characteristics of each message. Each of these tests has a numerical weight. When a message is analyzed by Antispam, the weights from all the spam tests that matched the message are added up and converted to a spam score that expresses the message’s “spam probability.” If a message’s spam probability is greater than the set threshold for what is spam, it is copied to the Antispam Quarantine. The exact threshold is constantly being monitored and adjusted for optimum spam filtering. Antispam also alters the message’s Subject heading to label it as spam ([SPAM:XXXXXXXX]). It also adds an “X-PerlMx-Spam” header to the message which contains the spam probability of the message. The sender’s email address of each message is also checked against various blacklists and whitelists. If the address is matched on a blacklist, the message is automatically discarded or quarantined. If the address is matched on a whitelist, the mess
