How to Block PST Files for the New Outlook for Windows

An OWA mailbox setting is available to block PST access for the new Outlook for Windows client. The setting mimics controls available for Outlook classic, where companies have been blocking PST access for a long time. Once email is in a PST, it’s invisible to any of the compliance solutions that organizations pay for. It’s also invisible to Copilot, which might not be a bad thing…

https://office365itpros.com/2025/06/09/block-pst-access-new-outlook/