Outlook Outage: Microsoft Says Exchange Online Issue May Hit Any Region

A widespread Outlook outage hit Microsoft customers on Thursday, Nov. 12. Microsoft says some users cannot connect to their Exchange Online mailboxes, the service behind Outlook email for businesses and other organizations, and that the problem may affect Microsoft 365 connectivity for users in any region. As of 2:07 p.m. ET, Microsoft’s service health records still listed the issue as an active service degradation.

The company says the trouble stems from elevated load on part of its infrastructure across multiple regions. Engineers are restarting and repairing affected systems and shifting traffic to other infrastructure, according to Microsoft’s updates. Microsoft has not given an estimate for when service will be fully restored.

What happened

Microsoft’s incident record for EX1550543 lists a start time of 11:17 a.m. ET on Thursday. At 12:54 p.m. ET, the company’s Microsoft 365 Status account on X wrote: “We’re investigating reports of users experiencing issues accessing Exchange Online mailboxes through multiple connection methods in the Americas.” Thirteen minutes later it widened that warning, saying it had “confirmed the issue may affect Microsoft 365 service connectivity for users in any region.”

Microsoft’s service health notice lists the connection methods that may be affected: Outlook on the web, Messaging API (MAPI), which Outlook for Windows uses, Exchange ActiveSync (EAS), used by many phone mail apps, and the REST API used by some apps and integrations.

At about 1:26 p.m. ET Microsoft opened a broader incident, MO1550821, titled “Users may be unable to connect to multiple Microsoft 365 services.” It lists Exchange Online, Microsoft Teams, SharePoint Online, Microsoft 365 Copilot and Microsoft Defender XDR as potentially affected services.

What Microsoft is saying

In its first MO1550821 notice at 1:27 p.m. ET, Microsoft said it had “determined the affected infrastructure is experiencing elevated load across multiple regions, which is likely contributing to the connectivity errors.” The company said it was “restarting and repairing impacted portions of this infrastructure to restore capacity, and reviewing an unexpected increase in a specific type of service traffic to determine whether it’s contributing to the elevated load.”

In later updates to EX1550543, Microsoft said it had redirected a portion of traffic away from the affected infrastructure in the U.S. and was evaluating the same step in other regions. At 1:43 p.m. ET it said it had found “a pattern in which affected servers are becoming intermittently unavailable, which places additional strain on the remaining infrastructure.” It said it had begun redistributing Outlook connection traffic across its broader worldwide infrastructure, which “may result in some latency,” and was “reviewing recent changes to identify the source of the increased traffic.”

At 1:57 p.m. ET, Microsoft said it had “completed redistributing Outlook connection traffic across our worldwide infrastructure” and was “moving additional traffic off the affected infrastructure to further reduce load.” It added that it was restarting affected servers to return them to service and “investigating whether the elevated traffic reflects a genuine increase in requests or a shift in how traffic is being routed across our infrastructure.”

Microsoft has not said the outage is the result of a cyberattack, and it has not published a root cause. Its incident record lists the root cause as not yet available.

How big is the Outlook outage?

Microsoft has not said how many customers are affected. Third-party outage tracker Downdetector, which collects problem reports submitted by users, gives a rough picture of the scale. Its figures are not confirmed outage counts and the actual number of affected users may vary.

Source: Downdetector figures as reported by Variety and Reuters. Downdetector counts are user-submitted reports, not confirmed outages. Table: LiveNewsWorld.

Variety reported that user reports of Outlook problems began spiking at around 12:39 p.m. ET, according to Downdetector. The National reported that Downdetector users around the world were also reporting problems with Teams and Copilot.

What Outlook and Microsoft 365 users can do now

• Check the official status first. Microsoft’s public Microsoft 365 service health page and the Microsoft 365 Status account on X carry the company’s updates. IT administrators can follow incidents EX1550543 and MO1550821 in the Microsoft 365 admin center. In its X posts, Microsoft pointed people to its public status site, status.cloud.microsoft, if the admin center is not available to them.
• Do not keep resending messages. Microsoft is shifting traffic between servers and has warned of some latency, so mail may be slow to send or arrive rather than lost. Check your Outbox and Sent Items before sending again.
• Try another way in, but expect the same problem. Microsoft says Outlook on the web, Outlook for Windows connections and mobile mail apps can all be affected, so switching apps may not help. Outlook desktop users with mail already downloaded to their device may still be able to read older messages offline.
• Use a backup channel for urgent work. Phone calls, text messages or another approved company tool can cover time-sensitive tasks while Microsoft 365 is unreliable. Teams may be affected too.
• Be careful with “fix your account” messages. Microsoft has not asked users to reset passwords or take any action on their accounts. Treat unexpected emails or texts that claim to restore your mailbox with suspicion, and review our guide on how to spot a phishing scam.

Background: an earlier Teams disruption

Thursday’s email problem followed a separate Microsoft Teams incident, TM1550488, earlier in the day. Microsoft posted on X at 10:40 a.m. ET that it was investigating Teams problems in North America. According to Microsoft’s final notice, users in the North and South America regions may have had delays or failures sending chat messages and loading conversations between 9:45 a.m. and 10:53 a.m. ET. Microsoft said at 12:09 p.m. ET that “customer impact is now fully resolved” and gave a preliminary root cause of “resource contention within the underlying service infrastructure.”

Microsoft has not said whether the Teams incident and the Exchange Online outage are related. Exchange Online is the hosted email and calendar service that sits behind Outlook for most Microsoft 365 business and enterprise customers. Deadline reported that business customers across sectors, including media companies, saw work slow down during the outage.

Timeline

All times are Eastern Time on Thursday, Nov. 12, 2026, from Microsoft’s service health notices and Microsoft 365 Status posts on X unless noted.

• 9:45 a.m.: Start of the separate Teams chat disruption (TM1550488), according to Microsoft.
• 10:53 a.m.: Teams disruption ends, according to Microsoft. It confirmed full resolution at 12:09 p.m.
• 11:17 a.m.: Start time listed for Exchange Online incident EX1550543. Microsoft posts an initial notice about potential mailbox access issues at 11:20 a.m.
• 12:39 p.m.: Outlook problem reports begin spiking on Downdetector, according to Variety.
• 12:54 p.m.: Microsoft 365 Status says on X that it is investigating Exchange Online mailbox access issues in the Americas.
• 1:07 p.m.: Microsoft says the issue may affect Microsoft 365 connectivity for users in any region.
• 1:19 p.m.: Microsoft says affected infrastructure is under elevated load across multiple regions and that it is restarting and repairing it.
• 1:26 p.m.: Microsoft opens MO1550821 covering Exchange Online, Teams, SharePoint Online, Microsoft 365 Copilot and Defender XDR.
• 1:27 p.m.: Downdetector shows more than 130,000 Outlook problem reports, according to Reuters.
• 1:29 p.m.: Microsoft says it has redirected a portion of U.S. traffic away from the affected infrastructure.
• 1:43 p.m. to 1:48 p.m.: Microsoft says affected servers are becoming intermittently unavailable and that it has begun redistributing connection traffic worldwide.
• 1:57 to 1:58 p.m.: Microsoft says it has completed the worldwide traffic redistribution, is moving more traffic off the affected infrastructure and is restarting affected servers.
• 2:07 p.m.: Both incidents still listed as active, with no cause or restoration time announced (LiveNewsWorld check).

Why it matters

Exchange Online and Teams are everyday work tools for many U.S. businesses, schools and government offices. When mailbox connections fail in the middle of a weekday, meetings, approvals, customer emails and security alerts can stall. The inclusion of Microsoft Defender XDR in Microsoft’s list of affected services also matters for IT and security teams that rely on its portal during the workday.

Microsoft’s own wording points to a capacity problem rather than a single broken feature: overloaded servers dropping in and out and pushing more traffic onto the rest of the system. Microsoft says it is still investigating whether the extra traffic is a genuine increase in requests or a change in how traffic is routed, and it has been reviewing recent changes, so the root cause is not yet known.

What happens next

Microsoft said its next update on the Exchange Online incident was due by 3 p.m. ET and that its next update on the wider Microsoft 365 incident would come by 4 p.m. ET. For the earlier Teams disruption, Microsoft promised a preliminary post-incident report within two business days. LiveNewsWorld will update this article as Microsoft reports progress. More technology coverage is on our Tech News page, and live news channels are on our Watch Live hub.

Frequently asked questions

Is Outlook down right now?

As of 2:07 p.m. ET on Thursday, Nov. 12, Microsoft’s service health records still listed the Exchange Online and Microsoft 365 connectivity incidents as active. Check Microsoft’s status page for the latest.

Is Microsoft down for everyone?

No. Microsoft says users “may” be unable to connect, which means some users and organizations are affected while others are not. It first described the problem as affecting the Americas and later said users in any region could be affected.

What caused the Microsoft 365 outage?

Microsoft has not published a root cause. It says part of its infrastructure is under elevated load across multiple regions and that it is investigating whether the extra traffic reflects a genuine increase in requests or a shift in how traffic is routed.

Was it a cyberattack?

Microsoft has not said the outage was caused by an attack. Its updates describe infrastructure load and connectivity errors.

Will I lose my email?

Microsoft has not reported any data loss. Its updates describe connection problems and possible latency while traffic is rebalanced, which typically means delays rather than lost messages.

Which Microsoft services are affected?

Microsoft lists Exchange Online, including Outlook connections, Microsoft Teams, SharePoint Online, Microsoft 365 Copilot and Microsoft Defender XDR as potentially affected.

Sources

• Microsoft 365 service health status (MO1550821), Microsoft
• Microsoft 365 Status on X, Nov. 12, 2026, 12:54 p.m. ET
• Microsoft 365 Status on X, Nov. 12, 2026, 1:48 p.m. ET
• Variety: Outlook Outage: Microsoft’s Email Service Goes Down Nationwide
• Reuters via CNA: Microsoft 365, Outlook down for thousands of US users, Downdetector shows
• Deadline: Microsoft Outlook Goes Down In 365 Outage
• The National: Outlook email outage affects users around the world