Microsoft 365 Alert – Service Degradation – Exchange Online – A limited number of users may be unable to send or receive email messages within Outlook on the web – RESOLVED

Announcements Habiba Tabasum

12/06/2023 09:32:00 AM (GMT)

NHSmail Reference : INC36323700

Microsoft Reference : EX580633

Issue Status : RESOLVED

Issue Description : Users may have been unable to send or receive email messages within Outlook on the web.

More info : This specifically impacted users that have Microsoft Defender for Cloud Apps (MDA) proxy controls via Chromium based browsers. Those who had access to the Firefox browser could’ have leveraged the browser as an alternative.

Final Update : 12/06/2023 09:32:00 AM – Microsoft disabled the offending change and after monitoring the service, they have verified that this action has successfully remediated the problem.

Scope of impact : Impact may have occurred for a limited number of users sending or receiving email messages within Outlook on the web when utilizing Microsoft Defender for Cloud Apps (MDA) proxy controls via Chromium based browsers.

Root cause : A recent Outlook on the web change to enable the analytics web worker for Chromium based browsers resulted in impact.

Next steps : They are investigating how the recent Outlook on the web change to enable the analytics web worker for Chromium based browsers resulted in impact to prevent this problem from happening again.