Blocked attachments in outlook

One of the most common ways of transmitting computer viruses is through file attachments. To help protect you and your recipients against computer viruses, Outlook blocks the sending and receiving of certain types of files (such as .exe and certain database files) as attachments. If you need to send one of these file types to an email recipient, we recommend using OneDrive and sending the recipient a link to the file instead.

Note: If you're using a Microsoft Exchange account, your email server administrator can unblock certain file types. Contact your administrator for more assistance.

Share your files safely

There are several ways to send and receive a blocked file. You can save the file to the cloud and send a link to the file, use a file compression utility like WinZip, or even rename the file with another extension, then have your recipient change the name back to the original name after they receive the file.

• Save the file to the cloud
  If you need to send a file that's blocked by Outlook, the simplest way to send your file is to upload it to OneDrive or a secure network share server such as SharePoint. Then send a link to the file. If you need to receive a blocked file, ask the sender to upload the file to OneDrive or SharePoint and send you a link. Once you receive the link, you can open the file location and download the file.
   

  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. You can right-click any file in Windows 7, Windows 8, or Windows 10 and select Send to compressed (zipped) folder. This creates a file with the same name as the original file, but the extension of .zip.

• Rename the file   
  You can rename the file (or request that the sender rename the file) to use an extension that Outlook doesn't block. For example, you can rename file.exe to file.docx. Once the renamed file is sent (or received), save it and rename it with the original extension using the following steps.

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.

Blocked file types in Outlook

Newer versions Office 2007

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

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
.aspx	Active Server Page Extended
.asx	ASF Redirector file
.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
.diagcab	Microsoft Support diagnostic tools
.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
.htc	HTML component file
.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
.msu	Windows Update file
.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
.printerexport	Printer backup file
.ps1	Windows PowerShell
.ps1xml	Windows PowerShell
.ps2	Windows PowerShell
.ps2xml	Windows PowerShell
.psc1	Windows PowerShell
.psc2	Windows PowerShell
.psd1	Windows PowerShell
.psdm1	Windows PowerShell
.pst	MS Exchange Address Book File, Outlook Personal Folder File (Microsoft)
.py	Python script
.pyc	Python script
.pyo	Python script
.pyw	Python script
.pyz	Python script
.pyzw	Python script
.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
.theme	Desktop theme file settings
.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
.vhd	Virtual Hard Disk
.vhdx	Virtual Hard Disk Extended
.vsmacros	Visual Studio .NET Binary-based Macro Project (Microsoft)
.vsw	Visio Workspace File (Microsoft)
.webpnp	Internet printing file
.website	Pinned site shortcut from Internet Explorer
.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

File types blocked in Outlook 2007

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	Help file index
.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
.hpj	Project file used to create 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
.osd	Application virtualized with Microsoft SoftGrid Sequencer
.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 VisualBasic 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
.xnk	Exchange Public Folder Shortcut