Does Virto Calendar App still work when Microsoft turns off EWS?
Context
Microsoft is retiring Exchange Web Services (EWS) in Exchange Online. It starts turning EWS off for all organizations in October 2026 and turns it off completely in April 2027 (Deprecation of Exchange Web Services in Exchange Online). Administrators may see alerts about applications that still use the EWS.AccessAsUser.All permission, including Virto Calendar App.
What Virto Calendar App uses EWS for
Virto Calendar App works with Microsoft 365 mainly through Microsoft Graph. Your own calendar, calendars shared with you and the categories of your own calendar come through Microsoft Graph and don’t depend on EWS.
The EWS.AccessAsUser.All permission is still needed for what Microsoft Graph does not offer:
- Public folder calendars. Microsoft has confirmed that public folders won’t be added to Microsoft Graph.
- Microsoft 365 group calendars: their categories and their settings in Virto Calendar App.
- Rooms and resources that Microsoft Graph does not find.
What happens when EWS is turned off in your tenant
- Public folder calendars are no longer shown. A message above the calendar says: “Public folder calendars can’t be shown: Exchange Web Services (EWS) is turned off in your Microsoft 365 organization.”
- Category colours of group calendars and the group calendar settings stop working. No message is shown.
- Rooms and resources that Microsoft Graph does not find are no longer shown.
Everything that comes through Microsoft Graph keeps working.
What to do
- Keep the
EWS.AccessAsUser.Allpermission granted. Virto Calendar App still needs it for the features above while EWS is on in your tenant. - To check whether EWS is still on in your organization, run
Get-OrganizationConfig | Format-List EwsEnabledin Exchange Online PowerShell (Control access to EWS in Exchange). - If your calendars show public folders, plan for them to disappear once EWS is turned off. Questions: support@virtosoftware.com.