Microsoft is addressing a known issue in Outlook that prevents users from opening encrypted emails sent from other organizations, displaying an error message related to Information Rights Management. A temporary workaround involves enabling cross-tenant access to trust MFA claims, allowing encrypted emails to be opened without errors, though both sending and receiving organizations must implement this fix. Microsoft is actively investigating the cause of the issue and promises further updates.

Microsoft is expanding the list of blocked attachments in Outlook Web and the new Outlook for Windows by adding .library-ms and .search-ms file types starting in July 2025. This decision aims to enhance security by preventing the exploitation of these file types in phishing attacks, although most organizations are unlikely to be affected. Users who need to send or receive these attachments can adjust their settings accordingly.