This section describes the Anti-Spam feature, including the SonicWall GRID Network, and how it interacts with SonicOS as a whole. The two points of significant connection with SonicOS are Address and Service Objects. You use the address and service objects to configure the Anti-Spam feature to function smoothly with SonicOS. For example, use the Anti-Spam Service Object to configure NAT policies to archive inbound email as well as sending it through a filter.
The Comprehensive Anti-Spam Service analyzes messages’ headers and contents and uses collaborative GRID printing to block spam email.
The GRID Connection Management with Sender IP Reputation feature is used by SonicWall Email Security and by the Anti-Spam service in SonicOS. GRID Network Sender IP Reputation is the reputation a particular IP address has with members of the SonicWall GRID Network. When this feature is enabled, email is not accepted from IP addresses with a bad reputation. When SonicOS does not accept a connection from a known bad IP address, mail from that IP address never reaches the email server.
GRID Network Sender IP Reputation checks the IP address of incoming connection requests against a series of lists and statistics to ensure that the connection has a probability of delivering valuable email. The lists are compiled using the collaborative intelligence of the SonicWall GRID Network. Known spammers are prevented from connecting to the firewall, and their junk email payloads never consume system resources on the targeted systems.
When a request is sent to your first-touch firewall, the Anti-Spam service evaluates the ‘reputation’ of the requestor. The reputation is compiled from white lists of known-good senders, block lists of known spammers, and denial-of-service thresholds.
If IP Reputation is enabled, the source IP address is checked in this order:
Only if the IP address passes all of these tests does the firewall allow that server to make a connection and transfer mail. If the IP address does not pass the tests, there is a message from SonicOS to the requesting server indicating that there is no SMTP server. The connection request is not accepted.