MI1017017: Microsoft 365 & Exchange Online Connectivity Issues

The Microsoft has resolved the issue with multiple Microsoft 365 services, and confirmed the fix to be stable.

Real-time updates can be viewed on their status page: https://status.cloud.microsoft/

Please report any continued issues with this service to your campus's IT helpdesk, and thank you again for your patience during the resolution of this issue!

Microsoft has not published any new updates, with the most recent one being as follows:

"Current status: We continue to observe sustained service recovery across the previously affected environments. Due to the severity of impact this incident caused, we're monitoring for an extended period to ensure no additional mitigative actions are required. In parallel, we're monitoring the backlog of email messages accrued during this event to ensure all process successfully before considering the issue resolved.

We're addressing all impact scenarios for dependent and related Microsoft 365 products as listed in the "More info" section below, and believe the majority of those impacted scenarios have been addressed."

Real-time updates can be viewed on their status page: https://status.cloud.microsoft/

We will be making updates as new information becomes available and at start-of-buisness (1:00 pm AK) tomorrow.
Thank you again for your patience.

Microsoft has published the following updates:

"Current status: We continue to observe sustained service recovery across the previously affected environments. Due to the severity of impact this incident caused, we're monitoring for an extended period to ensure no additional mitigative actions are required. In parallel, we're monitoring the backlog of email messages accrued during this event to ensure all process successfully before considering the issue resolved.

We're addressing all impact scenarios for dependent and related Microsoft 365 products as listed in the "More info" section below, and believe the majority of those impacted scenarios have been addressed."

Real-time updates can be viewed on their status page: https://status.cloud.microsoft/

We will be making updates as new information becomes available and at end-of-buisness (5:00 pm AK).
Thank you again for your patience.

Microsoft has published the following updates:

"Current status: We are deeply sorry for the disruption this incident has caused you and your business. We know the trust you place in our services and take that responsibility extremely seriously.

We are seeing broad recovery and stability across our services. This was a technical issue not related to cyber or AI / agents.

The incident was introduced by an issue during an earlier network capacity upgrade that surfaced following a recent network change. We have addressed the underlying issue and continue to restore service to remaining customers and regions.

Given the scale of demand, we restored services gradually, validating stability at each stage. While this took longer, it helped ensure a stable restoration. We will provide a full post-incident report once our review is complete."

Real-time updates can be viewed on their status page: https://status.cloud.microsoft/

We will be making updates as new information becomes available and at 3-hour intervals.
Thank you again for your patience.

Microsoft has published the following updates:

"Current status: We remain focused on addressing residual impact and ensuring reliable service restoration. We continue to assess recovery across various connection methods and are closely monitoring service health to verify sustained stability.

At this time, we have no evidence of malicious activity associated with this incident. We will continue to treat this with urgency until full mitigation, and we will share a full Post-Incident Report with root cause and defense-in-depth actions after mitigation is complete."

Real-time updates can be viewed on their status page: https://status.cloud.microsoft/

We will be making updates as new information becomes available and at 3-hour intervals.
Thank you again for your patience.

Microsoft has published the following updates:

"Current status: We’re seeing positive results with our efforts to restart affected infrastructure. We’re actively monitoring the performance of these to verify stability which will support improved availability. Remediation actions will be expanded as we confirm stability with the changes applied.

Previous status: Our investigation has found that a process on the affected servers responsible for establishing secure connections becomes overwhelmed, causing the servers to stop processing requests. We're preparing a configuration change to address this behavior that can be applied across all affected servers, and we're validating it on a subset of servers before applying it more broadly alongside restarts of the affected infrastructure. In parallel, we've begun reverting a recent network configuration change that correlates with the start of impact and are monitoring to determine whether this contributes to recovery. The temporary traffic limitations we previously described are now in effect in specific locations. We're monitoring the affected servers in those locations to confirm whether they remain stable while handling a narrower set of connections, after which we'll gradually reintroduce additional traffic."

Real-time updates can be viewed on their status page: https://status.cloud.microsoft/

We will be making updates at start-of-buisness (8:00 am AK) tomorrow.
Thank you again for your patience.

Microsoft has published the following updates:

"Current status: While the servers we've returned to service initially remain healthy, we've observed that they can become unresponsive again once they begin receiving traffic. We're analyzing diagnostic data from these servers with our networking and platform experts to determine what's triggering this behavior.

Building on the protective traffic management measures we've implemented, we're also temporarily limiting which types of traffic can reach the affected infrastructure in specific locations. This will help us determine whether a particular type of request is contributing to the impact and allow us to restore service incrementally. Additionally, we're rebuilding a subset of affected servers using a previous software configuration to validate whether this prevents them from becoming unresponsive, and we'll expand this approach to additional servers if we observe positive results.

Previous status: We've begun returning a portion of the affected servers to service, and they're remaining stable so far. We’ve also shifted traffic and connections to alternative pathways wherever possible and have observed limited recovery in some regions.

We've streamlined our recovery process to expedite returning the remaining affected servers to service. To further support recovery, we're implementing protective traffic management measures in a specific location to reduce load on the affected infrastructure, and we'll expand these measures to additional locations if we observe positive results. As capacity is restored, users may experience a gradual recovery as their clients reconnect to the service."

Real-time updates can be viewed on their status page: https://status.cloud.microsoft/

We will be making updates as new information becomes available and at end-of-buisness (5:00 pm AK).
Thank you again for your patience.

Microsoft has published the following updates:

We've validated an alternative health check method on a subset of affected infrastructure, which allowed the servers in that subset to successfully return to service, and we're now applying this change more broadly. We're also preparing an automated recovery process to continually detect and restart unresponsive servers, to help keep them in service while this change progresses. Additionally, our review of recent changes has identified a small number of configuration updates that we're investigating as potential contributors to the issue.

We're continuing to work through restarting and validating the affected servers to safely return them to service, and we're exploring opportunities to expedite this process. In parallel, we're assessing whether reverting the small number of recent configuration updates we identified could help accelerate recovery. Real-time updates can be viewed on their status page: https://status.cloud.microsoft/

We will be making updates as new information becomes available and at 3-hour intervals.
Thank you again for your patience.

Microsoft has published the following update:

Users may be unable to connect to multiple Microsoft 365 services.

Potentially impacted services include:
- Exchange Online
- Microsoft Teams
- SharePoint Online
- Microsoft Copilot 365
- Microsoft Defender XDR

Current status: We're aggressively pursuing all pathways to reduce impact. As a precaution, we've paused all deployments and configuration changes while we review recent changes for any correlation to this event. We've determined that the elevated load isn't driven by an overall increase in traffic, but by a large number of servers being unexpectedly unavailable, which is shifting load onto the remaining infrastructure. We're investigating what's causing these servers to become unavailable while we work to safely return them to service.

We will be making updates as new information becomes available and at 3-hour intervals.
Thank you again for your patience.

Microsoft is currently investigating an active service disruption preventing users from accessing Exchange Online mailboxes through multiple connection methods. Microsoft has confirmed that the underlying issue may affect broader Microsoft 365 service connectivity for users.

While desktop Office applications appear to be functioning normally at this time, web-based functions, cloud-dependent add-ins, and live syncing features may fail to connect.

We will be making updates as new information becomes available and at 3-hour intervals.
Thank you for your patience during the resolution of this issue!