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SpamAssassin by Alistair McDonald

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Anti-Spam Techniques

As the techniques to deliver spam have become more sophisticated, so have the techniques to detect and filter spam from legitimate email. The main techniques are described in the following sections. These techniques can be used on the email server by a system administrator, or an anti-spam service can be purchased from an external vendor.

Keyword Filters

Filters are based upon common words or phrases in an email body, for example 'buy', 'last chance', and 'Viagra'. SpamAssassin includes a variety of keyword filters and allows easy addition of new rules.

Open Relay Blacklists (ORBLs)

Open relay blacklists (ORBLs) are lists of open relays that have been reported and added to these blacklists after being tested. Anti-spam tools ...

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