Purpose
Microsoft is retiring Exchange Web Services in Exchange Online. This article explains what happens on the retirement dates, what ENow has already done about it, and the one step you need to take.
The short version: the work is done on our side, and there is one action for you after you upgrade.
The dates
- October 2026 — Microsoft begins disabling EWS globally for all organizations, blocking EWS requests from non-Microsoft applications to Exchange Online.
- April 2027 — EWS is fully disabled.
Two things worth being clear about, because both catch people out:
October is a rollout, not a single switch. Microsoft disables EWS progressively across organizations from October 2026. If nothing breaks for you in the first week of October, that does not mean your tenant is exempt — it means your turn has not come yet.
April 2027 is not your deadline. October is. By April there is nothing left to migrate, because it will already have stopped working.
What ENow has done
Every Exchange Online monitoring test in the ENow Management System has been migrated from EWS to Microsoft Graph. That includes:
- Mailbox sign-in tests
- Mail flow tests
- Free/busy tests
- Meeting tests
- Directory tests
- AutoDiscover tests
These tests keep running with EWS disabled in your tenant.
What is preserved
This is the part people most often ask about, because a monitoring platform is only as useful as its history.
Your thresholds, baselines, alert rules and historical latency data are preserved. There is nothing to reconfigure after you upgrade, and no gap in your trend history. Your charts run continuously across the migration — the underlying API changed, the measurements did not.
You do not need to re-tune, re-baseline, or rebuild alert rules.
What you need to do
1. Upgrade to the current GA release
Upgrade the ENow Management System to the current GA release. The Graph-based tests are included there.
If you are several versions behind, check the upgrade path before you start — a stepped upgrade through an intermediate release may be required rather than going straight to the latest.
2. Re-consent the Exchange Online Tester app registration
After upgrading, the Exchange Online Tester app registration needs to be re-consented so that it is granted the new Microsoft Graph permissions. The upgrade adds the permission requirements; the consent has to be granted in your tenant.
This step is required. Without it the tests have the code path but not the permissions, and they will fail once EWS stops answering.
3. Run Verify Credential
In the Admin Console, run Verify Credential to confirm the test account is working against the new permissions.
A successful verification is your confirmation that the migration is complete for your environment. Do not treat the upgrade alone as sufficient — run the check.
Confirming you are ready
Three things, in order:
- You are on the current GA release.
- The Exchange Online Tester app registration has been re-consented since that upgrade.
- Verify Credential passes in the Admin Console.
If all three are true, your Exchange Online tests will continue running when EWS is disabled in your tenant.
If tests start failing
If Exchange Online tests begin failing around or after the October 2026 rollout, work through the three checks above before anything else — in the great majority of cases the missing item is the re-consent in step 2, because an upgrade can complete successfully without it and nothing fails until EWS stops answering.
If all three check out and tests are still failing, open a case and say explicitly that you have completed the Graph migration steps and that Verify Credential passes. That rules out the common cause immediately.
References
- Microsoft Learn — Deprecation of Exchange Web Services in Exchange Online, for the current retirement timeline.
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