As cited
Copy frozen at (site build).
cloud saas
Microsoft extends the Outlook naughty step with two more file types
Microsoft is blocking .msix and .msixbundle file attachments in Outlook for Windows and Outlook on the Web starting in early to mid-November 2026 to prevent malicious Windows application packages from compromising devices. Administrators can allow these extensions in OwaMailboxPolicy if needed for legitimate business purposes. The action expands Outlook's existing blocked file list, which already includes .py, .ps1, and .cab files.
Why it matters: Exchange Online and New Outlook for Windows users will be unable to receive these attachments by default, potentially disrupting workflows that legitimately use .msix packages for software distribution; administrators must prepare policy changes if their organizations require these file types.
- Source published
- First seen by Cybersecurity Tracker
Source attribution
Correction
Correction recorded as of .
cloud saas
Microsoft extends the Outlook naughty step with two more file types
Microsoft is blocking .msix and .msixbundle file attachments in Outlook for Windows and Outlook on the Web starting in early to mid-November 2026 to prevent malicious Windows application packages from compromising devices. Administrators can allow these extensions in OwaMailboxPolicy if needed for legitimate business purposes. The action expands Outlook's existing blocked file list, which already includes .py, .ps1, and .cab files.
Why it matters: Exchange Online and New Outlook for Windows users will be unable to receive these attachments by default, potentially disrupting workflows that legitimately use .msix packages for software distribution; administrators must prepare policy changes if their organizations require these file types.
- Source published
- First seen by Cybersecurity Tracker