ePrism User Guide - EdgeWave

Pattern Based Message Filtering
Pattern Based Message Filtering
Pattern Based Message Filtering is the primary tool for whitelisting and blacklisting messages.
An administrator can specify that mail is rejected or whitelisted according to the contents of the
message header, including the sender, recipient, subject, and body text.
Pattern Based Message Filtering has the following main characteristics:
• Filters can be specified using simple English terms such as "contains" and "matches" or using
POSIX regular expressions
• Filters are processed in the order of their priority
• The actions can be used to modify the behavior of the STA spam filter
For example, you can create a simple text filter that specifies to check messages for the word
"FREE" in the subject. These types of filters can be helpful in correcting obvious disadvantages in
the other spam filters, but they can create problems of long term maintenance.
St. Bernard recommends that you use Pattern Based Message Filtering sparingly for anti-spam
purposes because it has three main disadvantages:
• Time required to specify and then maintain the rules
• Ease with which spammers can circumvent simple word matches
• Spammers fake the contents of the message headers
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