Kaspersky Secure Mail Gateway filters messages passing through the mail server to remove unsolicited mail (spam).
Messages are scanned for spam by the Anti-Spam engine. Anti-Spam engine scans each message for signs of spam. To do so, the Anti-Spam module first scans message attributes such as the addresses of the sender and recipient, message size, and headers (including the From and To headers). Second, Anti-Spam engine 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 application 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 a whole number from 0 to 100 that reflects the number of times Anti-Spam engine was actuated in processing the message. The application 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 application performs actions in accordance with the message processing rule settings. You can select actions to be performed by the application 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.
Anti-Spam functionality can be configured by editing the settings file for the Anti-Spam engine. 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 Secure Mail Gateway event log.
The settings file of the Anti-Spam engine can be accessed from the Kaspersky Secure Mail Gateway Management Console in Technical Support Mode with super-user account privileges.