Microsoft added more file extensions to Blocked file types in Outlook on the web

Microsoft has added few more around 38 files extensions to the Blocked file types in Outlook on the web. Previously, there were 104 file extensions were in the blocked file types in Outlook.

Once the file extensions are added to the blocked file types, then Outlook web users will not be able to download attachments that have those file extensions.

File extensions will be added to the BlockedFileTypes list

Below are the file extensions which will be added to the BlockedFileTypes list in the Outlook web.

Python scripting language:
“.py”, “.pyc”, “.pyo”, “.pyw”, “.pyz”, “.pyzw”

PowerShell scripting language:
“.ps1”, “.ps1xml”, “.ps2”, “.ps2xml”, “.psc1”, “.psc2”, “.psd1”, “.psdm1”, “.psd1”, “.psdm1”, “.cdxml”, “.pssc”

Windows ClickOnce

Microsoft Data Access Components (MDAC)

Windows sandbox

Digital certificates:
“.cer”, “.crt”, “.der”

Java programming language:
“.jar”, “.jnlp”

Other file extensions used by various applications:
“.appcontent-ms”, “.settingcontent-ms”, “.cnt”, “.hpj”, “.website”, “.webpnp”, “.mcf”, “.printerexport”, “.pl”, “.theme”, “.vbp”, “.xbap”, “.xll”, “.xnk”, “.msu”, “.diagcab”, “.grp”

These are file extensions which are very rarely used by organizations, so most organizations will not be affected by the change.

If you want a particular file type to be allowed, you can add that file type to the AllowedFileTypes property of your users’ OwaMailboxPolicy objects.

To add a file extension to the AllowedFileTypes list, you can use the below PowerShell script.

$policy = Get-OwaMailboxPolicy [policy name]
$allowedFileTypes = $policy.AllowedFileTypes
Set-OwaMailboxPolicy $policy -AllowedFileTypes $allowedFileTypes

Hope this will be helpful to know what are the new file extensions will be added to the blocked file types in Outlook web.

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Bijay Kumar

I am Bijay from Odisha, India. Currently working in my own venture TSInfo Technologies in Bangalore, India. I am Microsoft Office Servers and Services (SharePoint) MVP (5 times). I works in SharePoint 2016/2013/2010, SharePoint Online Office 365 etc. Check out My MVP Profile.. I also run popular SharePoint web site