Microsoft to block MSIX file attachments in Outlook starting November

Microsoft will block .msix and .msixbundle attachments in Outlook Web and the new Outlook Windows client beginning in November. The measure aims to…

Check if your organization sends or receives MSIX/MSIXBundle files through Outlook and establish alternative channels before November. If users report issues after the block is enforced, guide them toward secure distribution methods such as shared OneDrive or enterprise portals.