Purpose
This guide outlines the functional differences between Microsoft Exchange Web Services (EWS) and Microsoft Graph. It serves as a central hub for comparing legacy EWS behaviours with new Graph outcomes, ensuring a smooth transition for all users.
Background
Microsoft is officially deprecating EWS for Exchange Online on October 1, 2026. Beyond this date, third-party integrations relying on EWS will cease to function. Migrating to the Graph API is required to:
Maintain Service Continuity: Avoid sync interruptions after the deprecation deadline.
Enhance Security: Align with modern authentication and Microsoft’s latest security frameworks.
Future-Proof Workflows: Leverage Microsoft’s primary platform for all future 365 innovations.
Known Behaviour Changes
Here are some of the cases we have identified so far:
| Feature | Description | Date |
|---|---|---|
| Unsent Meetings with Classic Outlook | When the custom directive field This applies to meetings created in Classic Outlook where:
Under EWS, these meetings are correctly marked as not sent. This is a Microsoft Graph limitation, not a defect in Riva’s logic. Impact
Notes: Microsoft Graph does not expose a built-in |
7th May, 2026 |
|
|
Moving to Microsoft Graph changes how you recover deleted data. Unlike the older EWS connection, Graph removes the "SoftDelete" safety net for Calendar and Contacts. Additionally, Tasks can only be moved to the "Deleted Items" folder. If your team relies on recovering items from a secondary "hidden" bin, you’ll need to adjust your workflows, as that middle recovery step is no longer available. |
6th May, 2026 |
| Universal Change Detection for Tasks |
Universal Change Detection is currently not supported for Tasks with Microsoft Graph. Per Microsoft’s current architecture, change subscriptions for ToDo/Tasks are only supported via Delegated Permissions. They do not support Application-level permissions or impersonation. As Riva utilizes application authentication for security and scalability, UCD cannot support real-time Task subscriptions at this time. |
9th Dec, 2025 |
| Bi-directional calendar updates with attendees | Microsoft Graph API automatically triggers meeting invitations/updates to all attendees whenever an update is made to an event that contains participants. Riva can no longer suppress these notifications. | 3rd Oct, 2025 |
| Decline Appointment Polling | Decline Appointment Polling is now supported with the Microsoft Modern Exchange (Graph) Connector. It requires the Microsoft Graph application permissions MailboxFolder.Read.All and MailboxItem.Read.All. For Riva Cloud, existing customers must have an administrator grant consent for these newly added permissions before enabling the feature; new customers receive them during initial consent. For Riva On-Premise, customers add and consent to these permissions in their own Microsoft Entra application registration. |
31st Jul, 2026 |
| Calendar Sync Timeout Errors |
This is a known issue currently under investigation. After migration to Graph, calendar sync failures may occur for specific mailboxes when Microsoft Graph times out while processing mailbox calendar data. Microsoft has indicated that this can point to a service-side processing issue related to mailbox calendar data, rather than an issue with Riva’s sync logic or the customer’s configuration. Persistent Impact: Affected mailboxes may experience intermittent or repeated calendar sync failures, while other users in the same environment may continue syncing successfully. |
20th Jun, 2026 |
Next Steps
If you observe unexpected synchronization behaviour or encounter an issue not documented here, please submit a support ticket via Zendesk or contact the Riva support team for further assistance.
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