Exchange Online EWS outage?
Posted by EpicSimon@reddit | sysadmin | View on Reddit | 9 comments
Is anyone else in EU west region having issues with EWS in Exchange online since Wednesday?
Unfortunately we still have a few systems that require EWS which the software vendor hasnt updates to MS Graph yet.
Since Wednesday we're running into HTTP 403 on about half of our mailboxes, with no difference in configuration or permissions between those troublesome mailboxes and other working ones.
Project__5@reddit
Our current tenant setting for EWS is not configured (not true, nor false, just null) and about 50% of mailboxes have the user-specific EWS setting enabled. About 11 days ago (aligning with OP date) we started having backup issues (Datto's Backupify) and they're blaming the MS EWS thing.
crw2k@reddit
Microsoft said they were going to do random scream tests before Oct2026 unless you set your tenant EWSEnabled setting to True.
Borgquite@reddit
Source:
We may perform temporary “scream tests” (shorter periods of time when we turn EWS off and then back on) which can help expose hidden dependencies before the final cutoff. We will provide more information in the coming weeks. If your organization sets EWSEnabled = True now, you will not be impacted by any "scream tests" that we might conduct.
https://techcommunity.microsoft.com/blog/exchange/exchange-online-ews-your-time-is-almost-up/4492361
EpicSimon@reddit (OP)
Thanks for the hint, did this about 2 hours ago but no change yet. Guess it might only take effect starting from the next scream test?
EpicSimon@reddit (OP)
So what finally fixed this for me was enabling EWS per mailbox. The EwsEnabled flag in Get-OrganizationConfig did not do a thing in my environment. Instead I used the following command to enable EWS on a per-mailbox level, which ended up working. After about 15 mins EWS access for that Mailbox would work again.
Beware that this will reenable EWS for ALL mailboxes in the tenant!
Borgquite@reddit
I’m not sure what your experiencing is in fact one of the scream tests (they promised more info in the coming weeks; as far as I’m aware that hasn’t been provided yet, so it would be ‘brave’ of them to start already).
However if you’ve got EWSEnabled set I reckon you can rule that out after today.
Darking78@reddit
Sorry i ran a get-mailbox in powershell, that mightve caused the outage.
Worried-Bother4205@reddit
403s with identical configs usually point to a backend or policy rollout issue.
Worth checking service health and any recent auth policy changes on Microsoft’s side.
city_@reddit
I've seen since Wednesday that my Backup ( Synology Active Backup for 365) is failing to access the content of the emails with 403.
Tried a new application in entraid without success. Though it is an error on my side....