Introduction

Regular Expressions

What is a Regular Expression?
A Regular Expression is a sequence of characters that describe a pattern.

Regular expressions can be used in e-mail spam filtering to describe and help detect various forms of spam patterns. Patterns are specified with the use of  "wild card characters".

XGate uses the wild card characters: * and ?.

* = used to substitute multiple characters.
? = used to substitute a single character.

For example, if you wish to block the e-mail addresses:
test1@yahoo.com
test2@yahoo.com
test3@yaretoo.com

You would use the following regular expression to cover all these e-mail addresses: test?@ya*oo.com

Analogy
Wild Cards derive from card games. A wild card can be designated by its holder to any card they wish. In many card games, Jokers are the wild cards.

In the same way, in XGate, the wild cards that are used are the characters * and ?.

Regular Expression Details
To enter a regular expression, the following details are necessary:

Select
This can be either an E-mail Address or Domain.

E-mail Address/Domain
This is the e-mail address or domain, with wild card characters.

Action:
Choose whether to allow or block the specified e-mail address or domain regular expression.