Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish

Title: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish User impact: Users may have been unable to complete mailbox offboarding because the migration task is blocked and couldn’t finish. Final status: We've completed deployment of our fix faster than initially anticipated and validated after a period of monitoring service availability that our actions successfully remediated impact. Scope of impact: Users attempting to complete mailbox offboarding in Exchange Online may have been impacted by this issue. Start time: Tuesday, August 11, 2026, at 1:00 AM UTC End time: Thursday, August 27, 2026, at 1:00 AM UTC Root cause: The mailbox migration task was being delayed due to the integrity validation process remaining pending at the completion stage, resulting in impact. Next steps: - We're analyzing the offending integrity validation process to validate how it was introduced into our service and to confirm what actions we can take to prevent similar impact scenarios from occurring in the future.

Title: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish User impact: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish. Current status: We've initiated release of the subsequent fix and users should see relief as it progresses. We'll expect to provide a complete remediation timeline by the next scheduled update. Scope of impact: Users attempting to complete mailbox offboarding in Exchange Online may be impacted by this issue. This section may be updated as our investigation continues. Root cause: The mailbox migration task is being delayed due to the integrity validation process remaining pending at the completion stage, resulting in impact. Next update by: Thursday, August 27, 2026, at 7:30 PM UTC

Title: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish User impact: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish. Current status: Additional review indicates the issue isn't resolved for all affected users. We're continuing to prepare our code fix for deployment, and we'll aim to provide a timeline for it to begin by our next scheduled communications update. Scope of impact: Users attempting to complete mailbox offboarding in Exchange Online may be impacted by this issue. This section may be updated as our investigation continues. Root cause: The mailbox migration task is being delayed due to the integrity validation process remaining pending at the completion stage, resulting in impact. Next update by: Wednesday, August 26, 2026, at 7:30 PM UTC

Title: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish User impact: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish. Current status: While we're preparing our code fix for deployment, we're monitoring service health telemetry to confirm whether the mitigation we implemented to disable the affected integrity validation process has resolved the issue for all affected users. Scope of impact: Users attempting to complete mailbox offboarding in Exchange Online may be impacted by this issue. This section may be updated as our investigation continues. Root cause: The mailbox migration task is being delayed due to the integrity validation process remaining pending at the completion stage, resulting in impact. Next update by: Tuesday, August 25, 2026, at 10:00 PM UTC

Title: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish User impact: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish. Current status: We've been able to successfully disable the affected integrity validation process and resolve this issue for the majority of users. We're in the process of developing a code fix for the remaining impacted users and will provide an updated timeline on this final step in the remediation process as soon as it becomes available. Scope of impact: Users attempting to complete mailbox offboarding in Exchange Online may be impacted by this issue. This section may be updated as our investigation continues. Root cause: The mailbox migration task is being delayed due to the integrity validation process remained pending at the completion stage, resulting in impact. Next update by: Tuesday, August 25, 2026, at 8:00 PM UTC

Title: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish User impact: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish. Current status: We're continuing to run the commandlet to help disable the aforementioned integrity validation process. We'll share a completion timeline when one becomes available. Scope of impact: Users attempting to complete mailbox offboarding in Exchange Online may be impacted by this issue. This section may be updated as our investigation continues. Root cause: The mailbox migration task is being delayed due to the integrity validation process remained pending at the completion stage, resulting in impact. Next update by: Friday, August 21, 2026, at 7:00 PM UTC

Title: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish User impact: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish. Current status: We’re running a commandlet to help disable the aforementioned integrity validation process and anticipate by our next scheduled communications update that this process has completed. Scope of impact: Users attempting to complete mailbox offboarding in Exchange Online may be impacted by this issue. This section may be updated as our investigation continues. Root cause: The mailbox migration task is being delayed due to the integrity validation process remained pending at the completion stage, resulting in impact. Next update by: Friday, August 21, 2026, at 9:30 AM UTC

Title: Users may experience delays completing mailbox offboarding because the migration task is blocked and cannot finish User impact: Users may experience delays completing mailbox offboarding because the migration task is blocked and cannot finish. Current status: We're progressing with our analysis into the observed behavior and verifying the source for the unsuccessful completions of integrity validations. In parallel, we're determining the best option for disabling the “IsInteg” process, which is the integrity validation, in our effort to remediate the impact. Scope of impact: Impact is specific to some users in Asia Pacific region attempting to completing mailbox offboarding. Root cause: The mailbox migration task is being delayed due to the integrity validation process remained pending at the completion stage, resulting in impact. Next update by: Friday, August 21, 2026, at 4:00 AM UTC

Title: Users may experience delays completing mailbox offboarding because the migration task is blocked and cannot finish User impact: Users may experience delays completing mailbox offboarding because the migration task is blocked and cannot finish. Current status: We're continuing our investigation and evaluating mitigation options before proceeding with a broader disablement of the IsInteg process. In parallel, we're assessing whether the observed behaviour is the result of a recent regression to better understand the underlying issue and determine the most appropriate path forward. Scope of impact: Impact is specific to some users in Asia Pacific region attempting to completing mailbox offboarding. Root cause: The mailbox migration task is being delayed due to the integrity validation process remained pending at the completion stage, resulting in impact. Next update by: Thursday, August 20, 2026, at 9:00 PM UTC

Title: Users may experience delays completing mailbox offboarding because the migration task is blocked and cannot finish User impact: Users may experience delays completing mailbox offboarding because the migration task is blocked and cannot finish. Current status: We've identified that the mailbox migration task is being delayed due to the integrity validation process remained pending at the completion stage. We're disabling the integrity check for the affected mailboxes to remediate impact. We're monitoring the migration to confirm successful completion and validate that offboarding can proceed as expected. Scope of impact: Impact is specific to some users in Asia Pacific region attempting to completing mailbox offboarding. Root cause: The mailbox migration task is being delayed due to the integrity validation process remained pending at the completion stage, resulting in impact. Next update by: Thursday, August 20, 2026, at 2:30 PM UTC