Office 365 (Outlook on the Web) - Blocked File Attachment Types
Outlook on the Web by default blocks the attachment file types listed below.
However, a workaround is to use the Outlook desktop client (either on Mac or Windows) to download these blocked attachments.
.ace - Archive File Format
.ade - Access Project Extension (Microsoft)
.adp - Access Project (Microsoft)
.ani - Animated Mouse Cursors
.apk - Android Package File
.app - Executable Application
.appcontent-ms - Third-party Application
.appref-ms - Microsoft Component
.appx - Microsoft AppX Application Package
.arj - arj compressed file
.asp - Active Server Page
.aspx - Active Server Page Extended
.bas - BASIC Source Code
.bat - Batch Processing
.cab - Cabinet archive file
.cdxml - Windows PowerShell
.cer - Digital Certificate
.cer - Internet Security Certificate File
.chm - Compiled HTML Help
.cmd - DOS CP/M Command File, Command File for Windows NT
.cnt - Third-party Application
.com - Command
.cpl - Windows Control Panel Extension (Microsoft)
.crt - Certificate File
.crt - Digital Certificate
.csh - csh Script
.deb - Debian package format
.der - DER Encoded X509 Certificate File
.der - Digital Certificate
.dex - Dalvik executable format
.diagcab - Third-party Application
.dll - Dynamic link library
.docm - Microsoft Word Macro Enabled Document
.elf - Executable and linkable format
.exe - Executable File
.fxp - FoxPro Compiled Source (Microsoft)
.gadget - Windows Vista Gadget
.grp - Third-party Application
.hlp - Windows Help File
.hpj - Third-party Application
.hta - Hypertext Application
.img - Disk images
.inf - Information or Setup File
.ins - IIS Internet Communications Settings (Microsoft)
.iso - Disk images
.isp - IIS Internet Service Provider Settings (Microsoft)
.its - Internet Document Set, Internet Translation
.jar - Java File
.jnlp - Java File
.js - JavaScript Source Code
.jse - JScript Encoded Script File
.kext - macOS drivers
.ksh - UNIX Shell Script
.lha - Data compression file format
.lib - Linker input file
.library -
.lnk - Windows Shortcut File
.lzh - Data compression file format
.macho - Mach object file format
.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 - Third-party Application
.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)
.mhtml - MIME Html
.msc - Microsoft Management Console Snap-in Control File (Microsoft)
.msh - Microsoft Shell
.msh1 - Microsoft Shell
.msh1xml - Microsoft Shell
.msh2 - Microsoft Shell
.msh2xml - Microsoft Shell
.mshxml - Microsoft Shell
.msi - Windows Installer File
.msix - Windows app package
.msp - Windows Installer Update
.mst - Windows SDK Setup Transform Script
.msu - Third-party Application
.ops - Office Profile Settings File
.pcd- Visual Test (Microsoft)
.pif - Windows Program Information File (Microsoft)
.pl - Third-party Application
.plg - Developer Studio Build Log
.ppa - PowerPoint add-in
.ppam - PowerPoint add-in
.prf - Windows System File
.prg - Program File
.printerexport - Third-party Application
.ps1 - Windows PowerShell
.ps1xml - Windows PowerShell
.ps2 - Windows PowerShell
.ps2xml - Windows PowerShell
.psc1 - Windows PowerShell
.psc2 - Windows PowerShell
.psd1 - Windows PowerShell
.psdm1 - Windows PowerShell
.pssc - Windows PowerShell
.pst - MS Exchange Address Book File, Outlook Personal Folder File (Microsoft)
.py - Python File
.pyc - Python File
.pyo - Python File
.pyw - Python File
.pyz - Python File
.pyzw - Python File
.reg - Registration Information/Key for W95/98, Registry Data File
.rev - RAR Recovery volume set
.scf - Windows Explorer Command
.scr - Windows Screen Saver
.sct - Windows Script Component, Foxpro Screen (Microsoft)
.settingcontent-ms - Third-party Application
.shb - Windows Shortcut into a Document
.shs - Shell Scrap Object File
.sys - Device driver file
.theme - Third-party Application
.tmp- Temporary File/Folder
.udl - Microsoft Component
.uif -
.url - Internet Location
.vb - VBScript File or Any Visual Basic Source
.vbe - VBScript Encoded Script File
.vbp - Third-party Application
.vbs - VBSript Script File, Visual Basic for Applications Script
.vsmacros - Visual Studio .NET Binary-based Macro Project (Microsoft)
.vss - Visio Stencil
.vst - Virtual Studio Technology
.vsw - Visio Workspace File (Microsoft)
.vxd - Device driver file
.webpnp - Third-party Application
.website - Third-party Application
.ws - Windows Script File
.wsb - Microsoft Component
.wsc - Windows Script Component
.wsf - Windows Script File
.wsh - Windows Script Host Settings File
.xbap - Third-party Application
.xll - Third-party Application
.xml - Extensible Markup Language
.xnk - Third-party Application
.xz - Compressed archive
.z - Compressed archive