Microsoft 365 Alert – Service Degradation – Exchange Online – Users may be intermittently unable to connect to the Exchange Online service from the Outlook desktop app – RESOLVED

31/08/2023 08:42:00 AM (GMT)

NHSmail Reference : INC37974649

Microsoft Reference : EX671920

Issue Status : RESOLVED

Issue Description : Users may be intermittently unable to connect to the Exchange Online service from the Outlook desktop app.

More info : Impacted users may observe that the Outlook desktop app launches but fails to connect to Exchange Online. As a result, users can’t send or receive email messages. Affected users may be able to circumvent the issue by relaunching the Outlook desktop app after the problem occurs, or by using alternate connection methods, such as Outlook on the web.

Users may see the following status messages in the Outlook desktop app:
“Limited connectivity”
“Disconnected”

Final Update : 31/08/2023 12:00:00 PM – Microsoft successfully verified through their back-end telemetry that the revert was successful and have confirmed after a period of monitoring the environment that impact is remediated.

Scope of impact : Any users attempting to access their email from the Outlook desktop app may be intermittently impacted.

Root cause : A recent standard service update, intended to improve the performance of the Messaging API (MAPI) connection method inadvertently contained a regression, which resulted in intermittent connection issues to the Exchange Online service from the Outlook desktop app.

Next steps : Microsoft are reviewing their update procedures to better identify similar issues during the development and testing cycles.