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mediumExchangeupdatem365_message_center · Oct 5, 2026
Microsoft Outlook: Update to default blocked file types in OwaMailboxPolicy
Microsoft Outlook is updating the default blocked file types in OwaMailboxPolicy to enhance security, adding .msix and .msixbundle file types. This change affects administrators and security engineers.
“Services: Exchange Online. <p><b>[What and why]</b></p><p>To enhance security in Outlook on the web and new Outlook for Windows, we are updating the default list of blocked file types in OwaMailboxPolicy. As part of this update, the <code>.msix</code> and <code>.msixbundle</code> file types will be added to the Block…”
View original article →Security
threat_protection
Audience
adminsecurity_engineer
Environment
cloud
Classification confidence: 95%
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