Blocked attachments in Outlook

To help protect your computer, Outlook 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 will block these file types. If you're using Microsoft Exchange Server, typically only the email server administrator can unblock these file types.

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, save the file to the cloud, 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 or the cloud   
  You might want to ask the sender to save the attachment to the cloud, a server, or an FTP site that you can access. This can include OneDrive or 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. 
   

  Note: For OneDrive and OneDrive for Business, you'll need to ask the sender to only send you a link to the file rather than attach the file to the email using OneDrive. To obtain a sharing link in OneDrive, highlight the file and choose Get Link in the menu bar.

• 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 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.

Change which file types are blocked

Note: This content is applicable to Outlook 2016, Outlook 2013, and Outlook 2010.

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 about blocked attachments in Outlook.

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
.cnt	Microsoft Help Workshop Application
.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
.grp	Microsoft program group
.hlp	Windows Help File
.hpj	AppWizard Help project
.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
.jar	Java Archive
.jnlp	Java Network Launch Protocol
.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)
.mcf	Media Container Format
.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
.osd	Open Software Description
.pcd	Visual Test (Microsoft)
.pif	Windows Program Information File (Microsoft)
.pl	Perl script
.plg	Developer Studio Build Log
.prf	Windows System File
.prg	Program File
.ps1	Windows PowerShell
.ps1xml	Windows PowerShell
.ps2	Windows PowerShell
.ps2xml	Windows PowerShell
.psc1	Windows PowerShell
.psc2	Windows PowerShell
.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
.tmp	Temporary File/Folder
.url	Internet Location
.vb	VBScript File or Any Visual Basic Source
.vbe	VBScript Encoded Script File
.vbp	Visual Basic project 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
.xbap	Browser applications
.xll	Excel add-in
.xnk	Exchange Public Folder Shortcut