Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

The MIME structure of the message. The MIME structure of the message 
determines which part of the message is treated as “body,” and which part of 
the message is treated as an “attachment”. Many message filters are 
configured to act on just the body or just the attachment part of the message. 
For more information, see 

.

The threshold score configured for the regular expression. When you 
match a regular expression, you configure a “score” to tally up the number of 
times a match must occur before a filter action is taken. This allows you to 
“weight” the responses to different terms. For more information, see 

.

The structure of the query. When evaluating AND or OR tests within 
message filters, AsyncOS does not evaluate unneeded tests. In addition, it is 
important to note that the system does not evaluate the tests from left to right. 
Instead, when AND and OR tests are evaluated, the least expensive test is 
evaluated first. For more information, see 

Message filters are kept in an ordered list and numbered by their position in the 
list. When a message is processed, the message filters are applied in the associated 
numeric order. Therefore, filter number 30 will not have a chance to alter the 
source host of a message if filter number 9 has already executed a final action on 
(for example, bounced) the message. The position of a filter in the list can be 
changed via the system user interfaces. Filters imported via a file are ordered 
based on their relative order in the imported file.

After a final action, no further actions may be taken on the message. 

Although a message may match a filter rule, the filter may not act upon that 
message for any of the following reasons:

The filter is inactive. 

The filter is invalid. 

The filter has been superseded by an earlier filter that executed a final action 
for the message.