💡 Our Technical Review in summary
Summary
Users are experiencing intermittent issues accessing their Exchange Online mailboxes. The problem originated from a recent service update intended to introduce a new virtual account feature, which has caused connectivity degradation across specific connection methods.
Impact
Impact is intermittent and limited to users attempting to connect via the following platforms:
- Outlook Mobile Apps: Both Android and iOS versions are affected.
- Outlook for Mac: Specifically the “new Outlook for Mac” desktop client.
Status
Current Action: Microsoft has confirmed the root cause and is currently disabling the problematic change across all affected environments.
Background: While preliminary infrastructure restarts provided temporary relief, they did not offer a permanent fix. Reverting the service change is the primary remediation path. Microsoft is monitoring the environment and will provide a resolution timeline once the rollback is further progressed.
Incident Start Time: Thursday, March 12, 2026, 12:00 AM UTC.
Microsoft Official Issue Details
User Impact
Users may be intermittently unable to access their Exchange Online mailboxes in some connection methods.
Status: serviceDegradation
Service: Exchange Online
Classification: incident
Origin: microsoft
Updates
- 2026-03-21 18:03
Title: Some users may be intermittently unable to access their Exchange Online mailboxes in some connection methodsUser 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 are attempting to access the Exchange Online service through the Outlook mobile apps or the new Outlook for Mac desktop client.
Current status: After further assessment, we’ve confirmed that the identified change within the Exchange Online service intended to introduce a new virtual account resulted in impact. To remediate this issue, we’re disabling the change across the affected environments. Once available, we’ll provide a resolution timeline.
Scope of impact: Impact may occur for some users intermittently and users may be unable to access their Exchange Online mailboxes with the Outlook mobile apps.
Start time: Thursday, March 12, 2026, at 12:00 AM UTC
Root cause: A recent change within the Exchange Online service intended to introduce a new virtual account resulted in impact.
Next update by: Monday, March 23, 2026, at 6:30 PM UTC
- 2026-03-20 17:36
Title: Some users may be intermittently unable to access their Exchange Online mailboxes in some connection methodsUser 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 are attempting to access the Exchange Online service through the Outlook mobile apps or the new Outlook for Mac desktop client.
Current status: While we’ve previously identified that restarting the affected infrastructure isn’t a sufficient fix for this issue on a wide scale; we’ve confirmed that it does provide immediate temporary relief. We’re continuing to implement the temporary fix as needed while we test a possible long-term solution to resolve the underlying issue for all impacted users. Furthermore, we’re performing a deeper analysis into understanding the specifics of the root cause, and we’ll provide further details once they are identified.
Scope of impact: Impact may occur for some users intermittently and users may be unable to access their Exchange Online mailboxes with the Outlook mobile apps.
Start time: Thursday, March 12, 2026, at 12:00 AM UTC
Next update by: Saturday, March 21, 2026, at 7:00 PM UTC
- 2026-03-19 22:18
Title: Some users may be intermittently unable to access their Exchange Online mailboxes in some connection methodsUser 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 are attempting to access the Exchange Online service through the Outlook mobile apps or the new Outlook for Mac desktop client.
Current status: We’ve identified that restarting the affected infrastructure isn’t a sufficient fix for this issue and we’re continuing our investigation to identify and validate an appropriate remediation action. Once available, we’ll provide a timeline for resolution.
Scope of impact: Impact may occur for some users intermittently and users may be unable to access their Exchange Online mailboxes with the Outlook mobile apps.
Start time: Thursday, March 12, 2026, at 12:00 AM UTC
Next update by: Friday, March 20, 2026, at 6:30 PM UTC
- 2026-03-19 17:58
Title: Some users may be intermittently unable to access their Exchange Online mailboxes in some connection methodsUser 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 are attempting to access the Exchange Online service through the Outlook mobile apps or the new Outlook for Mac desktop client.
Current status: We’ve identified that a recent change within the Exchange Online service intended to introduce a new virtual account resulted in impact. To remediate this, we’re restarting the affected infrastructure and monitoring the progression to ensure successful resolution.
Scope of impact: Impact may occur for some users intermittently unable to access their Exchange Online mailboxes with the Outlook mobile apps.
Start time: Thursday, March 12, 2026, at 12:00 AM UTC
Root cause: A recent change within the Exchange Online service intended to introduce a new virtual account resulted in impact.
Next update by: Thursday, March 19, 2026, at 11:30 PM UTC
- 2026-03-19 16:19
Title: Some users may be intermittently unable to access their Exchange Online mailboxes with the Outlook mobile appsUser impact: Users may be intermittently unable to access their Exchange Online mailboxes with the Outlook mobile apps.
More info: This issue impacts both the Android and iOS mobile app experiences.
Current status: We’re continuing our review of Outlook mobile logs and service telemetry to isolate the source of the issue and determine appropriate remediation actions.
Scope of impact: Impact may occur for some users intermittently unable to access their Exchange Online mailboxes with the Outlook mobile apps.
Next update by: Thursday, March 19, 2026, at 6:30 PM UTC
- 2026-03-19 14:23
Title: Some users may be intermittently unable to access their Exchange Online mailboxes with the Outlook mobile appsUser impact: Users may be intermittently unable to access their Exchange Online mailboxes with the Outlook mobile apps.
More info: This issue impacts both the Android and iOS mobile app experiences.
Current status: We’re analyzing Outlook mobile logs to isolate the root cause of impact and establish a fix.
Scope of impact: Impact may occur for some users intermittently unable to access their Exchange Online mailboxes with the Outlook mobile apps.
Next update by: Thursday, March 19, 2026, at 4:30 PM UTC
