Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

You can use filters to search for strings and patterns in non-ASCII encoded message content (both 
headers and bodies). Specifically, the system supports regular expression (regex) searching for 
non-ASCII character sets within: 

Message headers

MIME attachment filename strings 

Message body: 

Bodies without MIME headers (i.e. traditional email) 

Bodies with MIME headers indicating encoding but no MIME parts

Multi-part MIME messages with encoding indicated

All of the above without the encoding specified in a MIME header

You can use regular expressions (regexes) to match on any part of the message or body, including 
matching attachments. The various attachment types include text, HTML, MS Word, Excel, and others. 
Examples of character sets of interest include gb2312, HZ, EUC, JIS, Shift-JIS, Big5, and Unicode. 

The token 

(?i)

 that indicates the rest of the regular expression should 

be treated in case-insensitive mode. Placing this token at the beginning 
of a case-sensitive regular expression results in a completely 
insensitive match.

For example, the regular expression “

(?i)viagra

” matches 

Viagra

, 

vIaGrA

, and 

VIAGRA

.

The regular expression notation that indicates the number of repetitions 
of the previous token is supported. 

For example, the expression “

fo{2,3}

” matches 

foo

 and 

fooo

 but not 

fo

 or 

fofo

.

This statement: 

if(header('To') == "^.{500,}")

looks for a “To” 

header that has 500 or more characters in it. 

Alternation, or the “or” operator. If A and B are regular expressions, the 
expression “

A|B

” will match any string that matches either “A” or “B.” 

For example, the expression “

foo|bar

” will match either 

foo

 or 

bar

, 

but not 

foobar

.