Outage in Microsoft 365
Users may have been intermittently unable to access their Exchange Online mailboxes in some connection methods.
Resolved Minor
April 02, 2026 - Started 28 days ago
- Lasted 1 day
Incident Report
Summary AI Generated
Microsoft 365 users experienced intermittent issues accessing their Exchange Online mailboxes through Outlook mobile apps and the new Outlook for Mac desktop client over a 33-hour period. The incident was caused by problems with the Notification Broker service in the Exchange Online infrastructure. Microsoft resolved the issue by restarting the Notification Broker service across affected infrastructure and implementing code changes to address contributing factors.
Title: Users may be intermittently unable to access their Exchange Online mailboxes in some connection methods
User impact: Users may be intermittently unable to access their Exchange Online mailboxes in some connection methods.
More info: This issue may intermittently impact some users who attempted to access the Exchange Online service through the Outlook mobile apps or the new Outlook for Mac desktop client.
Current status: We've received reports from affected tenants that the impact scenario originally communicated through SHD EX1256020 is still ongoing. We're working to restart the Notification Broker service on affected portions of Exchange Online service infrastructure to remediate impact while we continue our analysis into the underlying root cause.
Scope of impact: Impact may occur intermittently for some users accessing their Exchange Online mailboxes in the Outlook mobile apps or the new Outlook for Mac desktop client. This section may be updated as our investigation progresses.
Next update by: Thursday, April 2, 2026, at 11:30 PM UTC
Components affected
Exchange OnlineTrusted by 1,000+ teams
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Latest Updates ( sorted recent to last )
27 days ago - at 04/03/2026 07:19PM
Title: Users may have been intermittently unable to access their Exchange Online mailboxes in some connection methods.
User impact: Users may be intermittently unable to access their Exchange Online mailboxes in some connection methods.
More info: This issue may intermittently impact some users who attempt to access the Exchange Online service through the Outlook mobile apps or the new Outlook for Mac desktop client.
Current status: We've confirmed that the Notification Broker service restarted throughout the affected infrastructure and is successfully alleviating the majority of impact for users. We're also developing a code change and a revert on a recent service update to address additional issues that are contributing to impact while we continue our investigation into the underlying root cause.
Scope of impact: Impact may occur intermittently for some users accessing their Exchange Online mailboxes in the Outlook mobile apps or the new Outlook for Mac desktop client. This section may be updated as our investigation progresses.
Next update by: Tuesday, April 7, 2026, at 8:00 PM UTC
28 days ago - at 04/02/2026 11:15PM
Title: Users may be intermittently unable to access their Exchange Online mailboxes in some connection methods
User impact: Users may be intermittently unable to access their Exchange Online mailboxes in some connection methods.
More info: This issue may intermittently impact some users who attempt to access the Exchange Online service through the Outlook mobile apps or the new Outlook for Mac desktop client.
Current status: We're finalizing our process to restart the Notification Broker service across the affected infrastructure, which we anticipate may remediate the impact. In parallel, we're assessing options to implement long-term mitigation and telemetry to prevent further instances of impact while we continue our investigation into the underlying root cause.
Scope of impact: Impact may occur intermittently for some users accessing their Exchange Online mailboxes in the Outlook mobile apps or the new Outlook for Mac desktop client. This section may be updated as our investigation progresses.
Next update by: Friday, April 3, 2026, at 8:00 PM UTC
28 days ago - at 04/02/2026 07:15PM
Title: Users may be intermittently unable to access their Exchange Online mailboxes in some connection methods
User impact: Users may be intermittently unable to access their Exchange Online mailboxes in some connection methods.
More info: This issue may intermittently impact some users who attempted to access the Exchange Online service through the Outlook mobile apps or the new Outlook for Mac desktop client.
Current status: We've received reports from affected tenants that the impact scenario originally communicated through SHD EX1256020 is still ongoing. We're working to restart the Notification Broker service on affected portions of Exchange Online service infrastructure to remediate impact while we continue our analysis into the underlying root cause.
Scope of impact: Impact may occur intermittently for some users accessing their Exchange Online mailboxes in the Outlook mobile apps or the new Outlook for Mac desktop client. This section may be updated as our investigation progresses.
Next update by: Thursday, April 2, 2026, at 11:30 PM UTC
source IsDown
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