Microsoft Outlook Down Again? Thousands Report New Issues With Microsoft’s Email Service 3 Days In A Row

Microsoft Outlook users began reporting a fresh wave of access problems Wednesday morning, with outage-tracking site Downdetector logging a spike in complaints starting around 9:58 a.m. EDT, extending a multi-day stretch of intermittent disruptions tied to a broader Microsoft 365 authentication issue.

The outage tracker’s official account flagged the renewed surge in a social media post shortly after the reports began, asking affected users how the disruption was impacting them and directing people to its live outage map for updates. The hashtag “MicrosoftOutlookDown” quickly began circulating online as users compared notes on the latest round of email trouble.

Wednesday’s reports mark the third consecutive day in which Outlook users have experienced some form of disruption tied to the underlying incident, which Microsoft has been tracking internally under case number MO1465074. The company has said the root cause traces back to a problem within a core authentication configuration shared across multiple Microsoft 365 services, rather than an issue isolated to Outlook alone.

The disruption originally began at 3:08 p.m. UTC on Monday, Aug. 31, according to Microsoft, when users first reported delays and failures sending and receiving email, along with authentication errors and problems searching mailbox content. Reports on Downdetector that day surged past 5,000 within a few hours of the initial onset, with additional complaints flooding social media platforms throughout the day.

Microsoft said its investigation initially pointed to a misconfiguration affecting how authentication components were deployed across a portion of its infrastructure, a problem the company said it was working to isolate through service telemetry and diagnostic review.

“We’ve confirmed that users may experience degraded functionality with various Exchange Online functionalities. We’re reviewing service telemetry and diagnostic data to isolate the source of the issue,” Microsoft said in an update posted to its Microsoft 365 Status account as the outage was unfolding Sunday into Monday.

By Monday evening, Microsoft reported that mail flow was gradually improving for affected users, though search functionality within Outlook remained degraded well into the night. The company said shortly after 3 a.m. ET on Tuesday that it was beginning to see improvements in that search functionality as well, as engineers continued rolling out fixes to the underlying authentication systems.

Even as conditions improved, full resolution proved elusive. On Tuesday, Microsoft acknowledged that its mitigation work was ongoing rather than complete.

“Our mitigation actions are continuing to progress within the remaining affected infrastructure,” Microsoft said in a Tuesday update. “Indications from telemetry remain positive, and we’ve confirmed service availability is improving. We’re entering a period of extended monitoring to ensure a full resolution is in place.”

By early Wednesday, Microsoft had indicated that service availability had stabilized significantly for most customers, reporting availability above 99% and stating that the majority of users should no longer be experiencing impact from the underlying issue. Wednesday morning’s renewed spike in Outlook-specific reports, however, suggests that some users continued to experience residual disruption even as the broader incident showed signs of resolution.

Independent outage-tracking services have separately noted that Outlook has experienced a pattern of intermittent reports throughout the week, distinct from, though related to, the larger authentication incident. One tracking service recorded a stream of Outlook-related reports beginning around 1:53 a.m. Eastern time on Tuesday, followed by another cluster of reports affecting hundreds of users around 1:35 p.m. that same day, illustrating the uneven, start-and-stop nature of the recovery process across the week.

Beyond Outlook itself, Microsoft has confirmed that the underlying authentication issue affected a range of other Microsoft 365 services this week, including OneDrive for Business, SharePoint Online, Microsoft Teams, Microsoft Purview, Microsoft Defender XDR, the Microsoft 365 Admin Center and Universal Print. The breadth of services affected reflects how deeply many Microsoft 365 products rely on shared authentication infrastructure, meaning a single underlying configuration problem can ripple outward to affect multiple, seemingly unrelated tools used across an organization.

For businesses that rely heavily on Outlook and Exchange Online for daily communication, disruptions of this scale can have significant practical consequences, delaying internal and external correspondence and, in some cases, preventing employees from accessing scheduling, search or mailbox functions entirely. This week’s outage adds to a pattern of significant Microsoft 365 disruptions recorded so far in 2026, including a separate incident in January that stretched for roughly ten hours and affected Outlook, Defender and Purview, with reports on Downdetector during that earlier episode topping 15,000 at the peak of the disruption.

Microsoft has continued directing affected customers to its official Microsoft 365 Status page and social media account for updates as monitoring continues. The company has not yet published a detailed post-incident report explaining the specific technical root cause of the authentication misconfiguration or outlining steps it plans to take to prevent similar multi-day disruptions in the future, though such retrospective reports typically follow major incidents once monitoring periods conclude and engineering teams complete a full review.

As of Wednesday late morning, it remained unclear how long the residual Outlook-specific disruptions reported since 9:58 a.m. would persist, or whether they represented a new, isolated issue separate from the broader authentication problem that has affected Microsoft 365 services since Monday. Users experiencing ongoing trouble were advised to monitor official Microsoft support channels alongside independent outage trackers for the latest updates on service restoration.