Microsoft 365 Alert – Service Degradation – Exchange Online – Users may receive a false alert indicating their archive mailbox has exceeded or approached their storage limit – ONGOING

06/01/2025 14:15:00 PM

NHSmail Reference: INC46717255

Microsoft Reference: EX1213825

Issue Status: ONGOING

Issue Description: Users may receive a false alert indicating their archive mailbox has exceeded or approached their storage limit.

More info: This notification is a false alert, and users can continue working as normal as no archive mailbox storage limits have been reached.

Current Update: 21/01/2026 15:35:00 AM – Microsoft are awaiting confirmation from a sample of affected users that the issue is fully remediated following deployment of the fix.

Scope of impact: Your organisation is affected by this event, and some users may receive a notification indicating their archive mailbox has exceeded or approached their storage limit.

Root cause: A recent code regression in the Exchange Online service caused the alerting logic for auto‑expanding archive mailboxes to incorrectly evaluate mailbox size thresholds, leading to incorrect alert notifications.

Next update by: Wednesday, January 21, 2026, at 04:00 PM UTC