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Time zone settings are incorrect or missing for multiple mailboxes in Microsoft 365


Multiple mailboxes in Microsoft 365 may have incorrect or missing time zone settings. This symptom applies to all kinds of mailboxes, such as user mailboxes, resource mailboxes, and equipment mailboxes.


To resolve this issue, bulk change the time zone info for mailboxes in Microsoft 365. To do this, follow these steps:

  1. Connect to Exchange Online by using remote PowerShell.

  2. Run the following Windows PowerShell commands:

    $users = Get-Mailbox -ResultSize unlimited -Filter{(RecipientTypeDetails -eq <RoomMailbox>)}
    $users | %{Set-MailboxRegionalConfiguration $_.Identity -TimeZone <Pacific Standard Time>}


    • You can replace "RoomMailbox" with another valid Exchange recipient type, such as "UserMailbox" or "EquipmentMailbox."
    • Replace "Pacific Standard Time" with the time zone that's appropriate for you.


For more information, see Set-MailboxRegionalConfiguration for more information.