Using wildcard characters to refine filters
Applies to: Forefront Protection for Exchange
You can use wildcard characters in order to have your filter match patterns in the file name, subject line, and sender-domain field. You can use any of the following wildcard characters to refine your filters.
Note
Wildcard syntax does not work with keyword filters.
| Syntax | Description |
|---|---|
* |
Matches any number of characters in a file name. You can use multiple asterisks. The following are some examples of usage:
|
? |
Matches any single character, because many malicious users insert extra characters between letters in order to spoof filters. For example, you can filter C-O-N-T-E-S-T with the following filter: C?O?N?T?E?S?T |
[set] |
A list of characters and ranges, enclosed in square brackets [abcdef]. Any single character in the specified set is matched. For example, the set is useful for creating a single rule to match when the number zero (0) is used instead of the letter o. Ozone and oz0ne can be filtered using oz[o0]ne. |
[^set] |
Used to exclude characters that you know are not used. |
[range] |
Used to indicate several possible values in a set. It is specified by a starting character, a hyphen (-), and an ending character. For example, klez[ad-gp] would match kleza, klezd, kleze, klezf, klezg, and klezp, but not klezb or klezr. |
\char |
Indicates that special characters are used literally (characters are: * ? [ ] - ^ < >). The backslash is called an escape character, which indicates that a reserved control character should be taken literally as a text character. For example, if you enter *hello*, you would usually expect to match hello anywhere in the file name. If you enter *\*hello\**, you would match *hello*. If you enter *\*hello\?\**, you would match *hello?*. Note You must use a \ before each special character. |
See Also
Concepts
Creating a file filter list
Creating a sender-domain filter list
Creating a subject line filter list