Kaspersky Security 8 for Linux Mail Server filters messages passing through the mail server to remove unsolicited mail (spam).
Messages are scanned for spam by the Anti-Spam module. The Anti-Spam module scans each message for signs of spam. First, the Anti-Spam module scans the attributes of the message, such as sender and recipient addresses, size, and headers (including the From and To fields). Second, the Anti-Spam module analyzes the message content (including the Subject header) and attached files. Anti-Spam engine is enabled by default. If required, you can disable the Anti-Spam engine or disable Anti-Spam scanning for any rule. You can also limit the size of messages to be scanned for spam.
Depending on the sensitivity level, the program assigns messages in which spam or probable spam has been detected the specific statuses in accordance with the spam rating calculated by Anti-Spam. Spam rating is an integer number from 0 to 100, which is a sum of points awarded to the message for each time the Anti-Spam module was triggered while processing the message. The program also takes into account the responses from the DNSBL, SURBL and UDS servers, SPF technology, and results of reputation filtering to assign the spam rating to messages.
Reputation filtering is a cloud service that uses a technology that determines the reputation of messages. Information about new kinds of spam appears in the cloud service sooner than in Anti-Spam module databases, making it possible to improve the speed and accuracy of spam detection.
Depending on the status assigned, the program performs actions in accordance with the message processing rule settings. You can select actions to be performed by the program on messages with a certain status and configure tags to be added to messages based on the Anti-Spam scanning result. The default action performed on messages is Skip.
Spam Confidence Level (hereinafter also referred to as the "SCL rating") is a spam probability assessment.
An SCL rating can take the following values:
Based on the scan results, the program adds the X-MS-Exchange-Organization-SCL X-header to the message. This header contains the SCL rating.
Anti-Spam functionality can be configured by editing the settings file for the Anti-Spam module. In the settings file, you can change, for example, statuses of Anti-Spam scanning of messages or the level of detail of email message information recorded in the Kaspersky Security 8 for Linux Mail Server audit and event logs.
The settings file of the Anti-Spam engine can be accessed from the Kaspersky Security 8 for Linux Mail Server Management Console in Technical Support Mode with super-user account privileges.