Users may be unable to access their mailbox using any connection methods

Title: Users may be unable to access their mailbox using any connection methods

User impact: Users may be unable to access their mailbox using any connection methods.

More info: Impacted connection methods include, but may not be limited to:
- Representational State Transfer (REST) API
- Outlook on the web
- Exchange ActiveSync (EAS)
- Messaging API (MAPI)

Current status: Our broad deployment of the expedited configuration change continues to steadily saturate in the affected infrastructure. We still anticipate full saturation by Thursday, July 10, at 7:00 PM UTC. We’re closely monitoring deployment progress and service health telemetry to ensure the recovery continues as expected.

Scope of impact: Users attempting to access their Exchange Online mailbox using any connection methods may be impacted.

Start time: Wednesday, July 9, 2025, at 10:20 PM UTC

Preliminary Root Cause: A recent service update to an authentication component is unintentionally preventing access for a subset of users, resulting in intermittent service unavailability.

Next update by: Thursday, July 10, 2025, at 7:30 PM UTC

The expedited configuration change has reached about 65 percent of affected infrastructure. We’re continuing to see a sharp increase in service availability worldwide as the deployment continues. We’re closely monitoring progress and anticipate full saturation, by Thursday, July 10, at 7:00 PM UTC.

This quick update is designed to give the latest information on this issue.

Title: Users may be unable to access their mailbox using any connection methods

User impact: Users may be unable to access their mailbox using any connection methods.

More info: Impacted connection methods include, but may not be limited to:
- Representational State Transfer (REST) API
- Outlook on the web
- Exchange ActiveSync (EAS)
- Messaging API (MAPI)

Current status: We’ve begun a broad expedited deployment of the configuration change across all affected infrastructure. We expect most impacted users will experience relief within the next two hours, as the fix saturates the environment. We’re closely monitoring service health telemetry to ensure the recovery continues as expected. We understand how impactful incidents of this type can be for your organization, and we're continuing to open any additional workstreams to expedite recovery and restore availability.

Scope of impact: Users attempting to access their Exchange Online mailbox using any connection methods may be impacted.

Start time: Wednesday, July 9, 2025, at 10:20 PM UTC

Preliminary Root Cause: A recent service update to an authentication component is unintentionally preventing access for a subset of users, resulting in intermittent service unavailability.

Next update by: Thursday, July 10, 2025, at 6:30 PM UTC

We've validated that the configuration change has been effective in resolving impact in targeted infrastructure. We've started deploying the expedited configuration change broadly worldwide to all affected infrastructure. We’re working to provide an estimated remediation timeline as soon as one becomes available.

This quick update is designed to give the latest information on this issue.

Title: Users may be unable to access their mailbox using any connection methods

User impact: Users may be unable to access their mailbox using any connection methods.

More info: Impacted connection methods include, but may not be limited to:
- Representational State Transfer (REST) API
- Outlook on the web
- Exchange ActiveSync (EAS)
- Messaging API (MAPI)

Current status: We're continuing to apply the configuration changes to fix the underlying problem and completing additional validation efforts to ensure authentication components are properly configured. In parallel to the current deployment of the configuration change fix, we're reviewing options to leverage an expedited deployment methodology in regions which are experiencing the highest levels of impact to provide the most effective relief where possible.

Scope of impact: Users attempting to access their Exchange Online mailbox using any connection methods may be impacted.

Start time: Wednesday, July 9, 2025, at 10:20 PM UTC

Preliminary Root Cause: A recent service update to an authentication component is unintentionally preventing access for a subset of users, resulting in intermittent service unavailability.

Next update by: Thursday, July 10, 2025, at 4:30 PM UTC

Title: Users may be unable to access their mailbox using any connection methods

User impact: Users may be unable to access their mailbox using any connection methods.

More info: Impacted connection methods include, but may not be limited to:
- Representational State Transfer (REST) API
- Outlook on the web
- Exchange ActiveSync (EAS)
- Messaging API (MAPI)

Current status: We’ve identified an issue with the fix. We’re applying configuration changes, restarting affected components and additional validations are underway to confirm that authentication components are properly configured.

Scope of impact: Users attempting to access their Exchange Online mailbox using any connection methods may be impacted.

Start time: Wednesday, July 9, 2025, at 10:20 PM UTC

Preliminary Root Cause: A recent service update to an authentication component is unintentionally preventing access for a subset of users, resulting in intermittent service unavailability.

Next update by: Thursday, July 10, 2025, at 2:00 PM UTC

Title: Users may be unable to access their mailbox using any connection methods

User impact: Users may be unable to access their mailbox using any connection methods.

More info: Impacted connection methods include, but may not be limited to:
- Representational State Transfer (REST) API
- Outlook on the web
- Exchange ActiveSync (EAS)
- Messaging API (MAPI)

Current status: Our deployment of the fix is progressing quicker than anticipated and we expect impact to gradually mitigate as it progresses. We believe the issue will be resolved by our next update time.

Scope of impact: Users attempting to access their Exchange Online mailbox using any connection methods may be impacted.

Start time: Wednesday, July 9, 2025, at 10:20 PM UTC

Preliminary Root Cause: A recent service update is unintentionally preventing access for a subset of users, resulting in intermittent service unavailability.

Next update by: Thursday, July 10, 2025, at 11:30 AM UTC

Title: Users may be unable to access their mailbox using any connection methods

User impact: Users may be unable to access their mailbox using any connection methods.

More info: Impacted connection methods include, but may not be limited to:
- Representational State Transfer (REST) API
- Outlook on the web
- Exchange ActiveSync (EAS)
- Messaging API (MAPI)

Current status: We've determined the cause of the issue and have started deployment of a fix. We expect the fix to take an extended period following our safe change management process.

Scope of impact: Users attempting to access their Exchange Online mailbox using any connection methods may be impacted.

Start time: Wednesday, July 9, 2025, at 10:20 PM UTC

Preliminary Root Cause: A recent service update is unintentionally preventing access for a subset of users, resulting in intermittent service unavailability.

Next update by: Thursday, July 10, 2025, at 10:30 AM UTC

Title: Users may be unable to access their mailbox using any connection methods

User impact: Users may be unable to access their mailbox using any connection methods.

More info: Impacted connection methods include, but may not be limited to:
- Representational State Transfer (REST) API
- Outlook on the web
- Exchange ActiveSync (EAS)
- Messaging API (MAPI)

Current status: Our investigation into the authentication issue is ongoing. We're further assessing the impact scenario to help inform our next steps to resolve impact.

Scope of impact: Users attempting to access their Exchange Online mailbox using any connection methods may be impacted.

Start time: Wednesday, July 9, 2025, at 10:20 PM UTC

Next update by: Thursday, July 10, 2025, at 5:30 AM UTC

Title: Users may be unable to access their mailbox using any connection methods

User impact: Users may be unable to access their mailbox using any connection methods.

More info: Impacted connection methods include, but may not be limited to:
- Representational State Transfer (REST) API
- Outlook on the web
- Exchange ActiveSync (EAS)
- Messaging API (MAPI)

Current status: We're continuing to investigate the impacted mailbox infrastructure and suspect an issue with an authentication component may be causing impact. We're further investigating the affected component to inform our next steps.

Scope of impact: Users attempting to access their Exchange Online mailbox using any connection methods may be impacted.

Start time: Wednesday, July 9, 2025, at 10:20 PM UTC

Next update by: Thursday, July 10, 2025, at 3:30 AM UTC

Title: Users may be unable to access their mailbox using any connection methods

User impact: Users may be unable to access their mailbox using any connection methods.

More info: Impacted connection methods include, but may not be limited to:
- Representational State Transfer (REST) API
- Outlook on the web
- Exchange ActiveSync (EAS)
- Messaging API (MAPI)

Current status: We've identified a portion of mailbox infrastructure which isn't performing as efficiently as expected, resulting in impact. We're investigating this further to better understand the issue and help inform our next troubleshooting steps.

Scope of impact: Users attempting to access their Exchange Online mailbox using any connection methods may be impacted.

Start time: Wednesday, July 9, 2025, at 10:20 PM UTC

Next update by: Thursday, July 10, 2025, at 1:30 AM UTC

Title: Potential issues accessing mailboxes via one or more connection methods

User impact: Users may experience errors or failures when accessing their mailbox via one or more Exchange Online connection methods.

Current status: We're investigating a potential issue and checking for impact to your organization. We'll provide an update within 60 minutes.