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Step 1: Route Inbound Mail to IPOP's Filtering
Server |
| All messages
sent to your email domain are automatically
routed to the Email Sifter server. We do this by
pointing the MX (mail exchanger) DNS record for
the domain to the IPOP server. |
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Step 2: Virus Scan |
Messages that
come into the ipop server are first scanned for
viruses. Messages containing viruses are
immediately deleted.
Viruses are detected using multiple scanners
from different vendors. Due to the difference in
times when virus definitions are released, using
definitions from multiple vendors greatly
increases the probability that a new virus will
be caught and deleted before it reaches your
internal mail server or the intended recipient. |
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Step 3: Spam Tests |
Each email
that passes the virus scan is then subjected to
a series of over 30 tests to detect the presence
of characteristics common to spam. In general,
the spam tests we perform answer the following
questions:
 Is the
sender's domain/address invalid?
Are the message headers improperly formatted?
Was the message sent from a mail server,
allowing spam to be routed through it?
Is the message's route to the recipient poorly
defined?
Is the sender a known spammer (i.e. on Spamcop
or other real-time black list)?
Do the subject and/or body of the email use
words that commonly appear in spam?
Each of the 30+ spam filtering tests has a
predefined weight associated with it. For each
test that a message fails, the weights of those
tests are added to determine its total weight. |
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| Step 4:
Multi-Level Filtering |
Based on its
total weight, each message is assigned a level
indicating the probability that it is spam and
is acted upon according to your preferences. You
also have the option to adjust the minimum and
maximum total weight at which messages are
assigned to each of these levels.
This Multi-Level Filtering approach is extremely
effective at keeping a very high percentage of
spam out of your internal mail systems while
minimizing the risk that a legitimate email
message will get blocked. |
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