Cisco Cisco Email Security Appliance C160 Mode D'Emploi

Each message injected into the Cisco appliance is processed through all message filters in order, unless 
you specify a final action, which stops the message from being processed further. (See 

.) Filters may also apply to all messages, and rules may also be combined using logical 

connectors (AND, OR, NOT).

Several of the atomic tests used to define rules use regular expression matching. Regular expressions can 
become complex. Use the following table as a guide for the applying of regular expressions within 
message filter rules:

url-category

Does the category of any URL in the message 
match the specified categories? 

See 

. 

attachment-corrupt

Does this message have an attachment that is 
corrupt?

See 

.

a.Attachment filtering is discussed in detail in the section 

. 

b.Content Dictionaries are discussed in the detail in the “Text Resources” chapter.

Regular expressions in filter rules match a string if the sequence of 
directives in the regular expression match any part of the string. 

For example, the regular expression 

Georg

 matches the string 

George 

Of The Jungle

, the string 

Georgy Porgy

, the string 

La Meson 

Georgette

 as well as 

Georg

. 

Rules containing the dollar sign character ($) only match the end of the 
string, and rules containing the caret symbol (

^

) only match the 

beginning of the string. 

For example, the regular expression 

^Georg$

 only matches the string 

Georg

. 

Searching for an empty header would look like this: 

"^$"

Rules containing characters, white space, and the at sign character (

@

) 

only match themselves explicitly. 

For example, the regular expression 

^George@admin$

 only matches the 

string 

George@admin

. 

Rules containing a period character (

.

) match any character (except a 

new line). 

For example, the regular expression 

^...admin$ 

matches the string 

macadmin

 as well as the string 

sunadmin

 but not 

win32admin

.