IronPort - advanced configuration guide

Chapter 6 Using Message Filters to Enforce Email Policies
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Note When matching an empty string, do not use “” as that actually matches all strings. Instead use “^$”. For
an example, see the second example in Subject Rule, page 6-21.
It is also important to remember that if you want to match a literal period, you must use an escaped period
in the regular expression. For example, the regular expression sun.com matches the string
thegodsunocommando, but the regular expression ^sun\.com$ only matched the string sun.com.
Technically, the style of regular expressions used are Python re Module style regular expressions. For
a more detailed discussion of Python style regular expressions, consult the Python Regular Expression
HOWTO, accessible from:
http://www.python.org/doc/howto/
Regular Expression and Non-ASCII Character Sets
n Tests
Case-sensitivity
In some languages, the concepts of a word or word boundary, or case do not exist.
Complex regular expressions that depend on concepts like what is or is not a character that would
compose a word (represented as “\w” in regex syntax) cause problems when the locale is unknown or if
the encoding is not known for certain.
Regular expressions can be tested for matching using the sequence == and for non-matching using the
sequence !=. For example:
rcpt-to == "^goober@dev\\.null\\....$" (matching)
rcpt-to != "^goober@dev\\.null\\....$" (non-matching)
Unless otherwise noted, regular expressions are case-sensitive. Thus, if your regular expression is
searching for foo, it does not match the pattern FOO or even Foo.
Cisco IronPort AsyncOS 7.6 for Email Advanced Configuration Guide
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