Say goodbye to .msix and .msixbundle files in your email (unless your admin whitelists them).
Microsoft announced that it will add .msix and .msixbundle attachments to the list of blocked attachments in Outlook Web and the new Outlook Windows client starting next month.
Windows Report on MSN
Outlook is cutting off MSIX attachments over security risks
Microsoft will block .msix and .msixbundle attachments in Outlook starting in November 2026 after repeated malware abuse.
Outlook will stop opening .msix attachments from November. Renaming the file defeats it, and the policy change lands in every European tenant by default.
Results that may be inaccessible to you are currently showing.
Hide inaccessible results