Microsoft is working on a solution for an outage in Exchange Online affecting users of Outlook for mobile and the new Outlook for Mac. The cause is a new virtual account introduced by Microsoft earlier. Restarting the affected infrastructure did not resolve the issue. Microsoft is now rolling back the change.
Since last Thursday, Microsoft has been investigating an outage in Exchange Online that is preventing mailbox access via Outlook for mobile and the new Outlook for Mac. Microsoft did not disclose exactly how many users are affected or in which regions the issue is occurring.
After the investigation, the finger pointed to a recent change: the introduction of a new virtual account in Exchange Online. An attempt to resolve the outage by restarting the infrastructure was unsuccessful. On Saturday, Microsoft began rolling back that change as a potential long-term solution.
Microsoft: Change Disabled in Affected Environments
“After further assessment, we’ve confirmed that the identified change within the Exchange Online service intended to introduce a new virtual account resulted in impact. To remediate this issue, we’re disabling the change across the affected environments. Once available, we’ll provide a resolution timeline,” Microsoft said.
This isn’t the first time this year that Exchange Online has stumbled. In January, a previous Exchange Online outage also affected users, temporarily blocking email via IMAP4. In November, a similar incident blocked access via the classic Outlook desktop client. Last week, Microsoft resolved yet another Exchange Online outage that prevented customers from accessing their mailboxes and calendars via Outlook on the web, Outlook desktop, and Exchange ActiveSync.
At the same time as that previous outage, Microsoft also addressed an issue with login access to Office.com and Microsoft 365 Copilot due to high traffic volume.
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