Filtering files by file extension


Applies to: Forefront Protection for Exchange

Topic Last Modified: 2010-05-11

You can filter e-mail attachments that have a certain file extension. To filter by file extension, create the filter list using the Filter files with specific name patterns option. In the file filter list, in the Filter criteria - by file name section, type an asterisk (*), add the extension on which you want to filter, and then add another * (this prevents files with extra characters appended after the file extension from bypassing the filter). Filter matching is not case-sensitive.

For example, to filter all files with an .exe extension, type the following file name: *.exe*.

It is recommended that you avoid using the * wildcard without specifying an extension and with all file types selected. This can result in every file being detected, regardless of the file name or extension.

When configuring filter lists in Forefront Protection 2010 for Exchange Server (FPE), we recommend that you create a file filter list for the transport scan that contains the file extensions of the file types that may potentially be infected by malware.

To create a file filter list containing potentially dangerous file extensions
  1. In the Forefront Protection 2010 for Exchange Server Administrator Console, click Policy Management, and then under the Filters section, click Configure.

  2. In the Filters – Filter Lists pane, click the Create button.

  3. In the Select Filter Type dialog box, select File and then click Next.

  4. In the Select Your Goal dialog box, select Filter files with specific name patterns and then click Next.

  5. In the Select File Names dialog box, specify the filter list name and filter details, and click Next when you are finished adding your criteria.

    1. In the Filter list name box, type a name for the new list.

    2. In the Filter criteria - by file name section, add the file extensions listed in the table at the end of this topic, and then click the Add button after each item. You can also add multiple file names on the same line, provided that they are separated by a comma. Or, you may want to add each item to a text file, placing each item on a separate line, and then import all the items by clicking the Import button. Each item should be added using the following format: *.extension*

  6. Click Next until you reach the Target dialog box. Review your settings (it is recommended that you keep the default values), and then click Create.

  7. Click Save.

The following table includes the file extensions that you should include as items in this file filter list. You should review this list periodically and update it as needed.



Type of file


Archive file


Microsoft Access project extension


Microsoft Access project


ACT! document template


Executable application


Active Server Page files


Archive file


Word files that always have macros


Microsoft Visual Basic class module


Batch file


Binary file


Batch to memory batch file


Computer based training




Compiled HTML help file


Microsoft Windows command script


Java class file


Microsoft MS-DOS program


Control Panel extension


Security certificate


Corel script file


Cascading Style Sheet file


DLL files


Driver files


Program executable


Outlook Express e-mail message


Font file


Help file


HTML program


HTML files


Setup information


Internet naming service


Internet communication settings


JScript file


JScript file


JScript encoded script file


Program library common object file format




Access database file


MDE database file


Archived Web page


Microsoft common console document


Microsoft Windows installer package


Math script object file


Microsoft Windows installer patch


Microsoft Visual test source files


Relocatable object code


Object Linking and Embedding control executable


OrgViewer file


Photo CD image, Microsoft Visual compiled script


CGI program


Shortcut to MS-DOS program


Palm Pilot resource file


Archive file


Registration entries


Screen saver


Windows script component


Shortcut into a document


Shell scrap object


AMI Pro macro


Macromedia files


System device driver


Archive file


Internet shortcut


VBScript file


Virtual device driver


Windows script component


Windows script file


Windows script host settings file


CLSID filter