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Gobarr's avatar
Gobarr
Copper Contributor
May 02, 2025

We have a hybrid setup with on prem exchange server and O365 exchange integration.

I recently converted a former employees mailbox to a shared mailbox and added delegation rights to their manager.  I waited about a week before removing the microsoft license and moving the account to a different OU -- "disabled accounts".  But then today the shared mailbox and user is no where to be found in the O365 exchange admin center or the on prem exchange admin center.  What happened?  I thought shared mailbox's didn't require a license.

exchange online
Exchange Server
hybrid

2 Replies

  • Matt-Apps4Rent's avatar
    Matt-Apps4Rent
    Iron Contributor
    May 30, 2025

    You moved the account to an OU that isn't synced with Azure AD. Since you're in a hybrid setup, that caused the account (and shared mailbox) to be removed from Microsoft 365 during the next sync. Shared mailboxes don’t need a license, but the account must stay in a synced OU to exist in the cloud.

  • Andres-Bohren's avatar
    Andres-Bohren
    Iron Contributor
    May 03, 2025

    Hi Gobarr ,
    Probably the OU "disabled accounts" is not synced by Entra connect sync or Cloud Sync to Entra ID.

    If there is no User, there is no way to attach the Exchange Attributes to a User and therefore there is no Mailbox.

    Maybe also have a look at the Holds instead of converting the Mailbox

    https://learn.microsoft.com/en-us/exchange/policy-and-compliance/holds/holds?view=exchserver-2019

    Kind Regards

    Andres

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