Outlook web

Microsoft blocked 38 file extensions in Outlook web to prevent user’s from downloading attachments with those files extensions.

Outlook contains built-in spam mail filter which prevents the junk mail getting into the inbox. Now Microsoft added 38 file extensions to BlockedFileTypes property of existing OwaMailboxPolicy objects.

Previously outlook blocked 104 file types, now Microsoft expanded it by adding additional 38 File types to enhance the security.

If these file types are added to outlook blocked extensions, then users are blocked from downloading the attachments with those file types.


Microsoft said that the “newly blocked file types are rarely used, so most organizations will not be affected by the change. However, if your users are sending and receiving affected attachments, they will report that they are no longer able to download them.”

Securing your email address is vital, in the digital world, the email address related to all activities that you do online.

Blocked Extensions – Outlook Web

Following are the new extension types blocked

Python Extensions : ".py", ".pyc", ".pyo", ".pyw", ".pyz", ".pyzw"
Powershell Extensions : ".ps1", ".ps1xml", ".ps2", ".ps2xml", ".psc1", ".psc2", ".psd1", ".psdm1", ".psd1", ".psdm1"
Digital Certificate Extension : ".cer", ".crt", ".der"
Java based Extensions : ".jar", ".jnlp"
Other Extensions : ".appcontent-ms", ".settingcontent-ms", ".cnt", ".hpj", ".website", ".webpnp", ".mcf", ".printerexport", ".pl", ".theme", ".vbp", ".xbap", ".xll", ".xnk", ".msu", ".diagcab", ".grp"

If you are using Microsoft Exchange Server account and if you want to Whitelist any blocked attachments, this can be done by contacting the administrator to make the changes in security.

If you are not using Exchange Server account, then it can be unlocked by editing windows registries.

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