Email Reputation technology determines spam based on the reputation of the originating Mail Transport Agent (MTA). This off-loads the task from the Security Server. With Email Reputation enabled, all inbound SMTP traffic is checked by the IP databases to see whether the originating IP address is clean or it has been listed as a known spam vector.
There are two service levels for Email Reputation. They are:
Standard: The Standard service uses a database that tracks the reputation of about two billion IP addresses. IP addresses that have been consistently associated with the delivery of spam messages are added to the database and rarely removed.
Advanced: The Advanced service level is a DNS, query-based service like the Standard service. At the core of this service is the standard reputation database, along with the dynamic reputation, real-time database that blocks messages from known and suspected sources of spam.
When an email message from a blocked or a suspected IP address is found, Email Reputation blocks the message before it reaches your gateway.