Guides to the EWS retirement and Microsoft Graph

For administrators

• Exchange Online EWS retirement: dates and what to do

  Microsoft’s schedule for switching EWS off in Exchange Online, how to keep an application running in the meantime, and a migration checklist.

• Your EWS app list: what to do with each application

  The EWS usage report and the EWSAllowedAppIDs list name applications by ID. How to tell who owns each one, who has to fix it, and what to do until then.

• EWS returns 403 in Exchange Online: causes and fixes

  An application suddenly gets 403 Forbidden from EWS in Exchange Online. The four settings that cause it, how to check each one, and how long the fix lasts.

For developers

• What changes when EWS Managed API code moves to Microsoft Graph

  Sending, meetings, search, sync, notifications, IDs and time: where Microsoft Graph behaves differently from EWS, measured on live Exchange Online.

• EWS streaming notifications in Microsoft Graph: what replaces them

  Microsoft Graph has webhooks and delta queries and no streaming connection. How EWS pull, push and streaming subscriptions map to Graph.

• EWS item IDs in Microsoft Graph: converting stored IDs and keeping them stable

  How to convert stored EWS item IDs to Microsoft Graph IDs, when Graph IDs change, what immutable IDs fix, and which ConvertId formats Graph lacks.

• EWS extended properties in Microsoft Graph

  How an EWS ExtendedPropertyDefinition maps to a Microsoft Graph extended property, how to read, write and filter by it, and what Graph cannot do.

• EWS impersonation in Microsoft Graph: application permissions and mailbox scope

  Microsoft Graph has no ImpersonatedUserId. How a service that impersonated users in EWS reaches mailboxes in Graph and stays limited to the ones it needs.

For software vendors

• One code base for Exchange Server and Exchange Online after EWS

  A product with customers on Exchange Server and Exchange Online needs EWS for one group and Microsoft Graph for the other. Three ways to build it.