ePrism
Spam Filtering
Appliance
ePrism is a
email filtering appliance that provides organisations with a total
spam email management solution.
ePrism delivers a unique combination of e-mail security, spam filtering,
anti-virus and email content control in a robust high-performance
appliance.
The appliance
is designed to be deployed between internal mail servers and the
Internet, ePrism supports standard mail protocols and features a
complete and robust set of security capabilities specifically designed
to protect against the full spectrum of e-mail security threats.
- CONTENT -
Filters for spam, viruses, malformed messages and undesirable
content.
- OPERATING
SYSTEM - Hardened, secure operating system resists attacks.
- MANAGEMENT
- Robust management options, easy to use and customise.
- PHYSICAL
- High performance, fault-tolerant appliance.
ePrism uses the
following mechanisms to process spam mail . . .
Realtime
Blackhole Lists (RBLs)
RBLs are databases
of known spammers (or servers reported as sources of spam). There
are many of these, and St. Bernard provides a list of the better
known ones. Some of these lists are free; others charge an access
fee.
The RBL mechanism
is based on the Domain Name Server (DNS). DNS is a data query service
used on the Internet for translating hostnames into Internet addresses.
Every server that attempts to connect to ePrism will be looked up
on the specified RBL servers using DNS. This makes it a low-cost
operation that does not impact performance. If the lookup succeeds,
then the server is listed as a spammer and the connection dropped.
Distributed
Checksum Clearinghouse (DCC)
DCC, or Distributed
Checksum Clearinghouse, is based on a number of open servers (rather
like the RBL scheme) that maintain databases of message checksums
(derived numeric values that uniquely identify a message).
Mail users and
Internet Service Providers all over the world submit checksums of
all messages received. The database records how many of each message
is submitted. If requested, the DCC server can return a count of
how many instances of a message has been recorded.
The ePrism Mail
Filter uses this count to determine the disposition of a message.
DCC can reduce
spam by up to 90% in many cases. It is almost entirely hands-free,
creates little overhead and can be configured to block, quarantine
or tag and deliver messages.
Statistical
Token Analysis (STA)
STA is a new,
sophisticated method of identifying spam based on content. It is
based on the latest application of Bayesian logic to the problem
of classifying mail by content.
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