Microsoft extends the Outlook naughty step with two more file types

Microsoft is tightening Outlook and Outlook on the Web by blocking .msix and .msixbundle attachments by default, reducing the risk that users will accidentally install malicious Windows application packages. For CIOs and IT leaders, this is another example of Microsoft shifting more email security controls into the platform, which lowers endpoint risk but may require policy exceptions for legitimate software distribution workflows. Organizations should review whether these package types are used internally and update mail policies before the November rollout to avoid business disruption.