Retirement of Exchange Web Services in Exchange Online

I'm here to voice similar concerns; this announcement frightens me because Oct 1 2026 is probably not enough time given there's no feature parity at the moment (we exclusively rely on EWS Calendaring APIs) and there's no clear indication of when known gaps will be filled. Announcing a fixed date without a clear release path makes very little sense and only increases our anxiety. What if these gaps are only filled by the middle of 2026? As someone here has pointed out - it's been 5 years and Graph API has not lived up to its potential / scope and we're now effectively in limbo. Known bugs in EWS are no longer patched (such as issues with legacy permissions / time zones), new features are no longer added (such as MS Teams support) and MS Graph only provides us with a partial set of features. EWS is essential (at the moment) for us to be able to provide an Outlook replacement on the mac when it comes to calendaring / events. Graph simply does not provide us with enough functionality at the moment. Most organizations are weary of enabling Graph API for 3rd parties because it seems to require them to enable organization-wide permissions which they're uncomfortable with (such as enabling MS Teams conference calls for third parties to manage).

I would urge those involved to reconsider and turn this into a tentative / flexible date so that if Graph isn't ready in time or is still missing features (which I feel it will), we should be able to make a case for an extension so that our users don't suffer.