Users keep getting meeting acceptance notifications for already accepted meetings and / or appointments.


We are having an issue with Migration Manager for Exchange where migrated users keep receiving meeting acceptance notifications for already accepted meetings. 

Any help is greatly appreciated.


  • Thanks JohnnyQuest - Unfortunately, our maintenance contract expired recently and I can't get to that KB. 

  • Mmmm... so you have no support for the product either.  Not a great place to be when working on a high profile project?

    Here's the meat of KB for you.


    This happens due to Microsoft Calendar Repairing Assistant sending these notification because it considers these meetings / appointments conflicting.

    Relevant resolution:  (may require some tweaks as this is old information)

    For all Office 365 mailboxes:
    Use PowerShell to create a remote session to Office 365 to execute the following commands:
    $cred= Get-Credential
    $o365= New-PsSession -ConfigurationName Microsoft.Exchange -ConnectionUri -Credential $cred -AllowRedirection -Authentication Basic
    Import-PsSession $o365 –Prefix o365
    Get-o365Mailbox -ResultSize unlimited | Set-o365Mailbox -CalendarRepairDisabled $true
    The Calendar Assistant is now disabled for all mailboxes in the Office 365 tenant. It can be enabled again after migration has been completed  by using this PowerShell command:
    Get-o365Mailbox -ResultSize unlimited | Set-o365Mailbox -CalendarRepairDisabled $false
  • Thanks JohnnyQuest - We are on Exchange on-premises but I'll give this a shot. Does the KB mention whether the culprit is the sender or receiver mailbox or the source or destination Exchange servers?

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