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  4. Outlook blocking certain attachments

Outlook blocking certain attachments

You may see an error in Outlook stating something like “Outlook blocked access to the following potentially unsafe attachment”. If you see this message then the sender sent you an attachment type that Outlook has deemed unsafe. If the attachment is legitimate then the sender will need to send as a different file type, such a .zip file.

Here’s a list of attachment types that are deemed “unsafe” by Outlook:


File extension      File type


.ade            Microsoft Access project extension 

.adp            Microsoft Access project 

.bas            Microsoft Visual Basic class module 

.bat            Batch file 

.chm           Compiled HTML Help file 

.cmd           Microsoft Windows NT Command script 

.com           Microsoft MS-DOS program 

.cpl            Control Panel extension 

.crt             Security certificate 

.exe           Program 

.hlp            Help file 

.hta            HTML program

.inf            Setup Information 

.ins            Internet Naming Service 

.isp            Internet Communication settings 

.js             JScript file 

.jse            Jscript Encoded Script file 

.lnk            Shortcut 

.mdb            Microsoft Access program 

.mde            Microsoft Access MDE database 

.msc            Microsoft Common Console document 

.msi            Microsoft Windows Installer package 

.msp            Microsoft Windows Installer patch 

.mst            Microsoft Visual Test source files 

.pcd            Photo CD image, Microsoft Visual compiled script 

.pif            Shortcut to MS-DOS program 

.reg            Registration entries 

.scr            Screen saver 

.sct            Windows Script Component 

.shb            Shell Scrap object

.shs            Shell Scrap object 

.url            Internet shortcut 

.vb             VBScript file 

.vbe            VBScript Encoded script file 

.vbs            VBScript file 

.wsc            Windows Script Component 

.wsf            Windows Script file 

.wsh            Windows Script Host Settings file 

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