Microsoft 365 Alert : Service Degradation – Exchange Online – Some users intermittently can’t send or open email messages via the Outlook desktop client and Outlook on the web – RESOLVED
29/07/2022 08:30:00 AM (BST)
Issue Reported : 12/07/2022 12:00:00 AM UTC
Microsoft Reference : EX405758
NHSmail Reference : INC30806825
Issue Status : RESOLVED
Issue Description : Some users were intermittently unable to send or open email via the Outlook desktop client and Outlook on the web.
More info : Affected users received a Non-Delivery Report (NDR) when attempting to send email messages. Depending on the client leveraged, NDRs may have contained the following messages:
“This message could not be sent. Try sending the message again later, or contact your network administrator.”
“Your message did not reach some or all of the intended recipients.”
Scope of impact : This issue impacted some users attempting to send email messages via the Outlook desktop client and Outlook on the web.
Final Update : 09/08/2022 11:22:00 AM – Microsoft’s fix to revert the affecting update has completed and they have confirmed via telemetry that message traffic has been restored, confirming impact resolution.
Root cause : A recent update intended to optimize traffic load balancing and improve email transport times introduced a code issue that’s leading to impact.
Next steps : Microsoft is reviewing their update validation and testing procedures to better understand how the code issue was missed to better prevent similar future impact.