Mails not visible after converting from Shared mailbox to regular mailbox

Question

There is an user whose mailbox we converted to shared mailbox for a period of six months while the user was on long leave, User joined back this week, so we converted the mailbox back to normal mailbox. It’s been 48 hours after the conversion, all the old data is no longer visible in the user’s mailbox and its showing as blank. Also, the mailbox storage is showing as free.

The following troubleshooting steps were attempted:

1. Verified the mailbox conversion from the Exchange Admin Center and Checked the user's license. Made the password reset.
2. Attempted to sign in again with the new password.
3. Checked Outlook Web Access (OWA) in incognito mode, reviewed the deleted folder and recoverable items folder, but found nothing.
4. Checked the Outlook desktop application version and ran related commands, but this did not resolve the issue.
5. Reviewed the user's archiving settings and found that archiving is not enabled.
6. Our organization has blocked the use of Outlook Web Access as per company policy.

The Mailbox user is very important to us and we need to have emails backed up.

Can anyone please let me know how to resolve the issue ?

Answer 1

This might be a backend issue. You may open a support ticket via the admin center for further analysis.

Answer 2

Hello, @Mohana Reddy,

Welcome to the Microsoft Q&A platform!

From your description, it seems that the lost emails are indeed important to your organization and you have taken some ways to try to recover the mailbox data.

Here are a few additional suggestions that might help resolve the issue:

1.Check the Retention Policies: Ensure that no retention policies are applied that might have caused the emails to be deleted or moved.

2.Run the Get-MailboxStatistics Command: This command can provide information about the mailbox, including the item count and size. It might help identify if the emails are still present but not visible.

Get-MailboxStatistics -Identity "UserMailbox" | Select-Object DisplayName,ItemCount,TotalItemSize

3.Check Litigation Hold or In-Place Hold: If the mailbox was on hold, the items should still be recoverable. You can check this in the Exchange Admin Center or using PowerShell:

Get-Mailbox -Identity <UserMailbox> | FL LitigationHoldEnabled, InPlaceHolds

4.Check for Corruption: Sometimes, mailbox corruption can cause items to disappear. Running a mailbox repair request might help:

New-MailboxRepairRequest -Mailbox "UserMailbox" -CorruptionType ProvisionedFolder,SearchFolder,AggregateCounts,FolderView

5.Restore from Backup: If your organization has mailbox backups, restoring from a recent backup might be the quickest way to recover the missing emails.

Hope the above methods will help you. If it fails, just as NoOneCan said, open a support ticket via the admin center for further analysis may be a best choice for you.

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Thank you for your support and understanding.

Best Wishes,

Alex Zhang