MC1511071 - Action required: Review property changes for Exchange Online scenarios

Microsoft 365 Message Center announcement MC1511071.

MS Message Center's Summary

Exchange Online is retiring specific properties within migration cmdlets starting in November 2026. Administrators must audit existing PowerShell scripts and automation workflows to identify any reliance on these deprecated properties. You should review the official documentation, update your code before the enforcement dates, and contact Microsoft Support if critical workflows cannot be adapted in time.

Administrator impact
Administrators must audit and update PowerShell scripts and automation that rely on the affected migration cmdlet properties.
End user impact
No direct end user impact is expected unless backend automation failures disrupt administrative workflows.
Importance
6/10: This is a planned deprecation requiring proactive code updates to prevent automation failures.

Changes to Get Mailbox and New Mailbox specifically with the Migration parameter

Microsoft Summary

Exchange Online is deprecating certain properties in Get-Mailbox -Migration and New-Mailbox -Migration cmdlets starting November 15, 2026. Organizations must review and update scripts or workflows using these properties before then to avoid disruptions. Full details and guidance are provided in the linked Microsoft documentation.

Message Center ID
MC1511071
Category
plan For Change
Severity
normal
Services
Exchange Online
Tags
Admin impact, Retirement
Published
2026-10-16
Last updated
2026-10-16
Expires
2027-02-15
Action required by
2026-11-15

[What and why:] As part of our ongoing Exchange Online management and directory modernization efforts, we're simplifying legacy management scenarios and removing properties. We are deprecating selected properties returned or used with the following Exchange Online PowerShell scenarios: Get-Mailbox -Migration New-Mailbox -Migration If your scripts, applications, or automation use these scenarios, review the affected properties and determine whether your workflows depend on them. The change will be introduced in two phases: Beginning November 15, 2026: Selected properties will no longer be returned in applicable Get-Mailbox -Migration and New-Mailbox -Migration responses. Beginning December 15, 2026: The affected properties will be blocked from being configured through applicable New-Mailbox -Migration scenarios. [Rollout schedule:] We will begin rolling out mid-November 2026 and expect to complete by mid-November 2026. [Impact on your organization:] Your organization may be affected if you have scripts, applications, third-party solutions, or operational workflows that use the affected properties with -Migration scenarios. For example, a script using: Get-Mailbox -Migration will no longer receive the affected properties in the returned object beginning November 10, 2026. This may affect automation that depends on those properties being present or expects a fixed set of properties in the response. If your workflows don't use any of the affected properties, no action is required. [Action required / Recommendations:] Before November 15, 2026: Review scripts, applications, and integrations that use Get-Mailbox -Migration, New-Mailbox -Migration, or Set-Mailbox -Migration. Review the published list of affected properties. Identify whether your workflows depend on any affected property. Update and test affected workflows to remove the dependency. For the complete list of affected properties and additional guidance, see: Changes to Get-Mailbox and New-Mailbox specifically with the Migration parameter | Microsoft Learn . Required Actions Review your -Migration workflows and make any required changes before November 15, 2026. If an affected property is required for your scenario and you can't remove the dependency, contact Microsoft Support and provide the property name, cmdlet, usage scenario, and expected impact.