Some users may be unable to send or receive Exchange Online email through the native macOS mail app

Title: Some users may be unable to send or receive Exchange Online email through the native macOS mail app

User impact: Users may be unable to send or receive Exchange Online email through the native macOS mail app.

Current status: We've identified that a service feature deployment affecting rate limitations contained changes resulting in impact. We're moving to disable the problematic changes and anticipate this should be fully in effect by our next scheduled update, at which point we'll verify the issue is resolved through internal telemetry.

Scope of impact: Some users attempting to access the native macOS mail app are impacted. This information may be updated as our investigation continues.

Start time: Wednesday, September 9, 2026, at 12:00 AM UTC

Root cause: A service feature deployment affecting rate limitations contained changes resulting in impact.

Next update by: Friday, September 11, 2026, at 4:30 AM UTC

Title: Some users are unable to send or receive Exchange Online email through the native macOS mail app

User impact: Users are unable to send or receive Exchange Online email through the native macOS mail app.

Current status: We've clarified that reporting users are seeing impact to the native mail app on macOS and updated the Title and User impact fields of this communication accordingly. We're reviewing service logs and telemetry data to gain insight into the underlying source of impact and determine our next steps.

Scope of impact: Your organization is affected by this event, and some users attempting to access the native macOS mail app are impacted. This information may be updated as our investigation continues.

Next update by: Friday, September 11, 2026, at 4:30 AM UTC

Title: Some users are unable to send or receive Exchange Online email through the native iOS mail app

User impact: Users are unable to send or recieve Exchange Online email through the native iOS mail app.

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