Update 9/22/2026: We have revised our plans and will not be enforcing EWS restrictions to Kiosk / Frontline licensed users. EWS access will be restricted as a part of the overall EWS deprecation time...
Updated Sep 22, 2026
Version 6.0
Blog Post
Will this also affect access to these mailboxes as an app, i.e. when an app registration has EWS.AccessAsUser.All and/or full_access_as_app permissions on Exchange, will it still be able to get to those user's mailbox content after March 1st 2026?
This is important, since this will break some (if not all) third party mailbox migration tools that still (forcibly) rely on EWS in their backend to access user mailbox data. There's still no complete feature parity between Graph and EWS, especially for these usage scenario's. E.g. there's still no access to archive mailboxes, even using the import/export api (which is also still in preview so 'not supported in production').
The announcement from Sep 2023(!) stated 'we are working [on this] and will provide an updated timeline in the coming months.', but from what I can tell, over 2 years later we're still waiting on that timeline?
I'm not sure you can have an Archive mailbox without an Exchange Plan 1 / 2, which in itself will support EWS.
But I agree, there was already a downtime for Veeam 365 that impacted all Kiosk / F3 licenses recently, meaning all backups were blocked. Unsure if this was a test change from Microsoft, but that needs to be taken into consideration with major backup or data migration providers (Veeam, HYCU, Quest, etc.).