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Trend Micro InterScan Messaging Security Virtual Appliance Administrator’s Guide
IP Filtering Service
9-2
The IP Filtering service has two individual components: Email Reputation and IP
Profiler.
• Email Reputation filters spam senders at the connection layer.
• IP Profiler helps protect the mail server from attacks with smart profiles from the
Intrusion Detection Service (IDS).
Tip: Trend Micro recommends deploying IP Filtering as the first line of defense in your
messaging infrastructure.
Although most email messaging systems have a multi-layer structure that often includes
some pre-existing IP blocking, spam filtering, and virus filtering, Trend Micro
recommends completely removing other IP blocking techniques from the messaging
environment. IP Filtering should act as the precursor to any application filtering you
might use.
Using Email Reputation
Trend Micro maintains a list of IP addresses belonging to known spam senders in a
central database. Email Reputation filters spam by blocking the IP addresses stored in
this database.
Preparing Your Message Transfer Agent for Use With
Email Reputation Services
Configure your MTA to perform the appropriate DNS queries for the type of Email
Reputation to which you subscribed.
• Standard: Blocks connections with a 550 level error code (“connection refused”).
The MTA returns this error code to the server initiating the connection because the
IP address is in the Standard Reputation database as a known spammer.