Google Message Security for Google Apps Administration Guide - Manual (Page 231)

Content Manager 231
Match Any IP Address in a Range
Notes • \W matches any character that’s not a letter, digit, or
underscore. It prevents the regex from matching
characters before or after the email address.
• ^ matches the start of a new line. Allows the regex to
match the address if it appears at the beginning of a line,
with no characters before it.
• $ matches the end of a line. Allows the regex to match
the address if it appears at the the end of a line, with no
characters after it.
• [\w.\-] matches any word character (a-z, A-Z, 0-9, or
an underscore), a period, a plus sign, or a hyphen.
These are the most commonly used valid characters in
the first part of an email address. Note that the
\-
(which indicates a hyphen) must occur last in the list of
characters within the square brackets.
• The \ before the dash and period “escapes” these
characters—that is, it indicates that the dash and period
are not a regex special characters themselves. Note that
there is no need to escape the period within the square
brackets.
• {0,25} indicates that from 0 to 25 characters in the
preceding character set can occur before the @ symbol.
Content Manager supports matching of up to 25
characters for each character set in a regular
expression.
• The (...) formatting groups the domains, and the |
character that separates them indicates an “or.”
Usage example Match any IP address within the range 192.168.1.0 to
192.168.1.255.
Regex
examples 1: 192\.168\.1\.
2: 192\.168\.1\.\d{1,3}