Here’s a complete and searchable list of the 120 file types that are blocked by Outlook (sending or receiving) or OneNote (embedding in a notebook).
These, mostly old and obsolete, types of file can be used by hackers to infect Windows computers. As a precaution, Outlook and Exchange Server block messages containing these files, unless the network administrator makes an exception.
A few file types are still in use. For example: .ASP and .ASPX web pages. .PS1 and other Powershell scripts. Many Microsoft Access files are also included – search for ‘Access’ to see them all.
Source: Microsoft plus some additional notes/keywords to help searches.
Use the Search box (right) to quickly find file type from the 120 blocked types – e.g. ‘PowerShell‘ or ‘Access‘.
| File name extension | File type |
|---|---|
| .ade | Access Project Extension (Microsoft) |
| .adp | Access Project (Microsoft) |
| .app | Executable Application |
| .application | ClickOnce Deployment Manifest File |
| .appref-ms | ClickOnce Application Reference File |
| .asp | Active Server Page – web page |
| .aspx | Active Server Page Extended – web page |
| .asx | ASF Redirector File |
| .bas | BASIC Source Code |
| .bat | Batch Processing |
| .bgi | Borland Graphics Interface |
| .cab | Windows Cabinet File |
| .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 Diagnostics Cabinet File |
| .exe | Executable File – program |
| .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) |
| .iso | Optical Disk Media File System |
| .isp | IIS Internet Service Provider Settings (Microsoft) |
| .its | Internet Document Set, Internet Translation |
| .jar | Java Archive |
| .jnlp | Java Network Launching 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 Addin |
| .xnk | Exchange Public Folder Shortcut |
