Blocked attachments in Outlook

To help protect your computer, Microsoft Outlook 2013 doesn’t 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. By default, Outlook blocks these files. See the section Attachment file types blocked in Outlook for a list of the file types blocked.

In this article

Share your files safely

Change which file types are blocked

Attachment file types blocked in Outlook

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 available without using Outlook, or make it less likely to be blocked by Outlook. The following are some safe ways to share files with people that 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 to 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 doesn’t recognize these file name extensions as potential threats. Therefore, it doesn’t 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 doesn’t 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 don’t 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 2013



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