Kaspersky Security 8 for Linux Mail Server supports 3 methods for integration with Postfix:
After-queue integration. In this case, all messages that pass through the protected server go to the application for scanning after insertion in the Postfix mail server queue.
Before-queue integration. With before-queue integration, messages go to the program for scanning before insertion in the Postfix mail server queue.
Integration using the Milter protocol. In this case, messages are forwarded to the program for scanning via the Milter protocol.