Blocked attachments in Outlook

To help protect your computer, Microsoft Outlook 2010 does not allow you to receive files of certain types (such as .exe files) as attachments, because of their potential for introducing a virus into your computer. Outlook blocks these files by default. See the section Attachment file types blocked in Outlook for a list of the file types blocked.

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Share your files safely

If you want to receive a file of a type that is blocked by Outlook, you can ask the sender to either make the file accessible without using Outlook, or make it less likely to be blocked by Outlook. Following are a few safe ways to share files with people you trust.

Use a shared server    You might want to ask the sender to save the attachment to a server or an FTP site that you can access. This can include a secure network share server such as SharePoint. The sender can send you a link to the attachment on the server or FTP site. You can click the link to access the file and save it on your computer.

Use a file compression utility    Using a compression utility, such as WinZip, creates a compressed archive file that has a different file name extension. Outlook does not recognize these file name extensions as potential threats. Therefore, it does not block the new attachment. Many third-party compression utilities are available.

Rename the file    You can request that the sender rename the attachment to use a file name extension that Outlook does not recognize as a threat. For example, an executable file that has the file name extension .exe could be renamed as a Word 2010 file that has a .docx file name extension.

Ask the sender to resend the renamed attachment to you. To save the attachment and rename it to use the original file name extension, do the following:

  1. Locate the attachment in the email message.
  2. Right-click the attachment, and then click Copy.
  3. Right-click the desktop, and then click Paste.
  4. Right-click the pasted file, and then click Rename.
  5. Rename the file to use the original file name extension, such as .exe.

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Change which file types are blocked

If you use a Microsoft Exchange Server account and the Exchange Server administrator has configured the Outlook security settings, the administrator might be able to help you. Ask the administrator to adjust the security settings on your mailbox to accept attachments such as the one that Outlook blocked.

If you do not use an Exchange Server account, there is an advanced procedure that you can use to unblock some file types. This procedure involves editing the registry in Windows. For more information about unblocking attachment file types, see the Microsoft Support article on blocked attachments in Outlook.

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Attachment file types blocked in Outlook

File name extension File type
.ade Access Project Extension (Microsoft)
.adp Access Project (Microsoft)
.app Executable Application
.asp Active Server Page
.bas BASIC Source Code
.bat Batch Processing
.cer Internet Security Certificate File
.chm Compiled HTML Help
.cmd DOS CP/M Command File, Command File for Windows NT
.com Command
.cpl Windows Control Panel Extension (Microsoft)
.crt Certificate File
.csh csh Script
.der DER Encoded X509 Certificate File
.exe Executable File
.fxp FoxPro Compiled Source (Microsoft)
.gadget Windows Vista gadget
.hlp Windows Help File
.hta Hypertext Application
.inf Information or Setup File
.ins IIS Internet Communications Settings (Microsoft)
.isp IIS Internet Service Provider Settings (Microsoft)
.its Internet Document Set, Internet Translation
.js JavaScript Source Code
.jse JScript Encoded Script File
.ksh UNIX Shell Script
.lnk Windows Shortcut File
.mad Access Module Shortcut (Microsoft)
.maf Access (Microsoft)
.mag Access Diagram Shortcut (Microsoft)
.mam Access Macro Shortcut (Microsoft)
.maq Access Query Shortcut (Microsoft)
.mar Access Report Shortcut (Microsoft)
.mas Access Stored Procedures (Microsoft)
.mat Access Table Shortcut (Microsoft)
.mau Media Attachment Unit
.mav Access View Shortcut (Microsoft)
.maw Access Data Access Page (Microsoft)
.mda Access Add-in (Microsoft), MDA Access 2 Workgroup (Microsoft)
.mdb Access Application (Microsoft), MDB Access Database (Microsoft)
.mde Access MDE Database File (Microsoft)
.mdt Access Add-in Data (Microsoft)
.mdw Access Workgroup Information (Microsoft)
.mdz Access Wizard Template (Microsoft)
.msc Microsoft Management Console Snap-in Control File (Microsoft)
.msh Microsoft Shell
.msh1 Microsoft Shell
.msh2 Microsoft Shell
.mshxml Microsoft Shell
.msh1xml Microsoft Shell
.msh2xml Microsoft Shell
.msi Windows Installer File (Microsoft)
.msp Windows Installer Update
.mst Windows SDK Setup Transform Script
.ops Office Profile Settings File
.pcd Visual Test (Microsoft)
.pif Windows Program Information File (Microsoft)
.plg Developer Studio Build Log
.prf Windows System File
.prg Program File
.pst MS Exchange Address Book File, Outlook Personal Folder File (Microsoft)
.reg Registration Information/Key for W95/98, Registry Data File
.scf Windows Explorer Command
.scr Windows Screen Saver
.sct Windows Script Component, Foxpro Screen (Microsoft)
.shb Windows Shortcut into a Document
.shs Shell Scrap Object File
.ps1 Windows PowerShell
.ps1xml Windows PowerShell
.ps2 Windows PowerShell
.ps2xml Windows PowerShell
.psc1 Windows PowerShell
.psc2 Windows PowerShell
.tmp Temporary File/Folder
.url Internet Location
.vb VBScript File or Any Visual Basic Source
.vbe VBScript Encoded Script File
.vbs VBScript Script File, Visual Basic for Applications Script
.vsmacros Visual Studio .NET Binary-based Macro Project (Microsoft)
.vsw Visio Workspace File (Microsoft)
.ws Windows Script File
.wsc Windows Script Component
.wsf Windows Script File
.wsh Windows Script Host Settings File
.xnk Exchange Public Folder Shortcut

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Applies to:
Outlook 2010