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Attachment file types restricted by Outlook 2010


Applies to: Office 2010

Topic Last Modified: 2012-02-29

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Some attachments in items (such as e-mail messages or appointments) in Microsoft Outlook 2010 have restricted access. Files that have specific extensions can be categorized as Level 1 (the user cannot view the file) or Level 2 (the user can open the file after saving it to disk).

By default, Outlook 2010 classifies several file types as Level 1 and blocks files that have those extensions from being received by users. As an administrator, you can use Group Policy to manage how a file type is categorized for e-mail attachment blocking. For example, you can change a file type categorization from Level 1 to Level 2 or create a list of Level 2 file types. There are no Level 2 file types by default. For more information, see Plan attachment settings in Outlook 2010.

The following table lists Level 1 file types that are blocked under a default installation of Outlook 2010.

File extension File type


Microsoft Access project extension


Microsoft Access project


Application file


Active server page


Microsoft Visual Basic class module


Batch file


Internet Security Certificate file


Compiled HTML Help file


DOS CP/M command file, Microsoft Windows NT command script


Windows Help contents file


Microsoft MS_DOS program


Control Panel extension


Security certificate


Script file


DER Encoded X509 certificate file


Executable file


Microsoft Visual FoxPro compiled program


Windows Gadget


Windows program group file


Help file


Help project file


HTML program


Information or setup file


Internet Naming Service


Internet Communication settings


Internet Document Set file


JAVA archive file


JavaScript source code


JScript Encoded script file


UNIX Shell script file


Windows shortcut


Microsoft Access module shortcut


Microsoft Access shortcut


Microsoft Access diagram shortcut


Microsoft Access macro shortcut


Microsoft Access query shortcut


Microsoft Access report shortcut


Microsoft Access stored procedures


Microsoft Access table shortcut


Media attachment unit


Microsoft Access view shortcut


Microsoft Access data access page


Manifest configuration file


Microsoft Access add-in program


Microsoft Access program


Microsoft Access MDE database file


Microsoft Access data file


Microsoft Access workgroup


Microsoft Access wizard program


Microsoft Common Console document


Windows PowerShell script helper


Windows PowerShell script helper


Windows PowerShell script helper


Windows PowerShell script helper


Windows PowerShell script helper


Windows PowerShell script helper


Windows Installer package


Windows Installer update package file


Visual Test source file


Microsoft Office profile settings file


Open software description file


Microsoft Visual Test compiled script


Windows program information file


Perl script file


Developer Studio build log


Outlook profile file


Program source file


Windows PowerShell


Windows PowerShell


Windows PowerShell


Windows PowerShell


Windows PowerShell


Windows PowerShell


Microsoft Outlook personal folder file


Registration entries, Registry data file


Windows Explorer command file


Windows screen saver


Windows script component


Windows shortcut to a document


Shell Scrap object file


Temporary file or folder


Uniform Resource Locator (Internet shortcut)


Microsoft Visual Basic Scripting Edition (VBScript) file


VBScript Encoded script file


Visual Basic project file


VBScript script file, Visual Basic for Applications script file


Microsoft Visual Studio .NET binary-based macro project file


Microsoft Visio workspace file


Windows script file


Windows script component


Windows script file


Windows Script Host settings file


XAML browser application


Microsoft Exchange public folder shortcut