Missing shared mailbox

Question

I'm coming to this late, but hopefully I have enough details to get this out coherently...

We had a terminated user's mailbox setup as shared, and the on-prem AD account was accidentally deleted a few months. We recovered the account from the AD trash and (supposedly) the mailbox was recovered as well.

As of this week, the users that are still accessing the mailbox no longer see it though, and it's missing from the shared mailbox list. The user is still in AD on-prem and in the 365 portal this time; we're just missing the mailbox. I've done a check against soft-deleted mailboxes, and it's not there either. 

Any thoughts? I know we should use holds on cases like this...one thing at a time.

Answer 1

Hi Andy,

I would suggest you try to use eDiscovery search to see if you can find these data in the mailbox. You can refer to the article below to create an in-place eDiscovery search:

https://technet.microsoft.com/en-us/library/dd353189(v=exchg.150).aspx

If the data can't be found, it would be lost.

Regards,

Yang

Answer 2

Hey Robert,

The mailbox would have been originally created in the Exchange Online environment, not on-prem. You are correct that it was converted to shared in the EAC. However, the mailbox does not show up in either the regular, shared, or soft-deleted lists.

Thanks,

Andy

Answer 3

Hi Amervis,

Thanks for the updates.

I'd like to know whether the shared mailbox was migrated to Exchange Online from your Exchange Server as a regular user mailbox and later converted to a shared mailbox through the Exchange admin center in Exchange Online. If yes, please try the steps below to fix the issue:

https://support.microsoft.com/en-us/help/2710029/shared-mailboxes-are-unexpectedly-converted-to-user-mailboxes-after-directory-synchronization-runs-in-an-exchange-hybrid-deployment

Regards,

Robert

Answer 4

Firstly, I’d like to confirm whether you have Exchange on-premise or not. If not, my understanding is that you synced the AD user account to Office 365 and then assigned an Exchange online license for the synced user account. As a result, this user account has a corresponding Exchange online mailbox. After that, the user mailbox was converted to a shared mailbox.

This is correct, Alan. When the user left the company, the mailbox was converted to shared and the license was removed. Normally we keep the mailbox shared for a month before the user account is deleted and the shared mailbox goes away at that point. In this case, the mailbox was needed for longer and so the account has remained active.

The AD account remains disabled but active today, but sometime since March 1, the shared mailbox has vanished. I am fairly certain that the mailbox is lost permanently, but I'd like to know if there's anything besides a soft-match check I can try?

Answer 5

Hi Amervis,

Firstly, I’d like to confirm whether you have Exchange on-premise or not. If not, my understanding is that you synced the AD user account to Office 365 and then assigned an Exchange online license for the synced user account. As a result, this user account has a corresponding Exchange online mailbox. After that, the user mailbox was converted to a shared mailbox.

Given the situation, I suggest you disable/delete the AD user account if you don’t need to manage this user locally. Then you can directly create a shared mailbox in Office 365 with the same address; if you need to manage the AD user locally, you can repeat the process of converting the shared mailbox in Office 365 online as the above paragraph mentioned.

If it is not your situation, please clarify it with more details. For example, how you got the shared mailbox previously.

Regards,

Alan