The Regular Expressions Primer is a tutorial for those completely new to regular expressions.
To familiarize you with regular expressions, this primer starts with the simple building blocks
of the syntax and, through examples, builds to construct complex expressions.
PureMessage uses regular expressions as follows:
- The Policy Script: Regular expressions can be used as match operators ("Matches
regex" and "Does not match regex") for many types of policy rule tests. For example, a
regular expression can be used to test the contents of a message's Envelope to
field. Certain policy rule actions also support the use of regular expressions. For example, the
"Deliver immediately for" action supports the use of a regular expression as a match type
for exceptions.
For information about using regular expressions while editing the policy
script via the PureMessage Manager, see "Policy Rule
Tests" and "Policy Rule Actions". If you are manually editing the policy script, see
pmx-policy (the documentation for the command-line interface to the
PureMessage policy engine).
When regular expressions are used in policy rule tests or actions, they are not prefixed or
suffixed with slashes or braces. However, if you are manually editing the policy script on the
command-line, you must "escape" backslashes and quotes within regular expressions by
preceding them with a backslash. (The PureMessage
Manager will automatically escape these characters.) For example, to search for the string
"and\or", enter "and\\or" as the regular expression. See "Searching for Special
Characters" for more information.
- Lists: Lists can be configured to contain regular expressions. When creating a new
list, specify the "Regular Expression" match type. Individual entries in the list are then
entered as regular expressions. They are not prefixed with slashes or braces. It is not
necessary to escape special characters in regular expressions contained in lists. For more
information about configuring lists, see "Lists".
- Anti-Spam Rules: Anti-spam rules support regular expressions as the test portion of
a rule. For example, the content of a message can be tested against a specified regular
expression. Many of the default anti-spam rules supplied with PureMessage are based on regular expressions; custom anti-spam
rules exclusively use regular expressions. For information about configuring anti-spam rules,
see "Spam Detection".