An employee has left and their account was deleted, but it turns out there were important emails in their mailbox. As long as the mailbox is still soft-deleted, you can restore its contents into another mailbox, such as their manager's or a shared mailbox. You don't have to bring the old user back, and you don't need an extra license for the person who left.
When is it possible?
When you delete a user in Microsoft 365, their mailbox is kept for 30 days as a soft-deleted mailbox. After that it's gone for good. There's one important exception: if a retention policy or Litigation Hold applied to the mailbox, it becomes an inactive mailbox. That one is kept as long as the policy applies, and you can restore it too.
The difference between soft and hard deletion is explained in delete a user in Microsoft 365: soft delete and hard delete.
Before you start
- You need an account with Exchange admin rights. If PowerShell doesn't recognise
New-MailboxRestoreRequest, the Mailbox Import Export role is usually missing. Assign it in the Exchange admin center under Roles > Admin roles and reconnect. - Pick the target mailbox deliberately. The restored mail becomes a normal part of that mailbox and counts towards its storage.
- Does the target mailbox have a retention policy that deletes or archives old mail? Put a retention hold on the target first, or old restored items could disappear straight away.
Restore the mailbox into another mailbox
- Connect to Exchange Online PowerShell with
Connect-ExchangeOnline. - Find the deleted mailbox and note its ExchangeGuid:
Get-Mailbox -SoftDeletedMailbox | Select DisplayName, PrimarySmtpAddress, ExchangeGuid - Find the ExchangeGuid of the target mailbox:
Get-Mailbox manager@yourdomain.com | Select ExchangeGuid - Start the restore, into a separate folder in the target mailbox:
New-MailboxRestoreRequest -SourceMailbox <deleted-GUID> -TargetMailbox <target-GUID> -TargetRootFolder "Mailbox Jan" -AllowLegacyDNMismatch - Follow the progress:
Get-MailboxRestoreRequest | Get-MailboxRestoreRequestStatistics
With -TargetRootFolder everything lands neatly under one folder. Leave it out and the folders are merged into the target's existing folders, which gets confusing fast. Once the status shows Completed, clean up the request with Remove-MailboxRestoreRequest.
Restore the archive
Did the user have an online archive? Restore it separately with -SourceIsArchive. Add -TargetIsArchive if it should go into the target's archive, and always use a -TargetRootFolder, or the items end up in places the user can't see.
An inactive mailbox
Find inactive mailboxes with Get-Mailbox -InactiveMailboxOnly and use the DistinguishedName as the source. Microsoft recommends adding the inactive mailbox's LegacyExchangeDN to the target as an X500 address first, instead of using -AllowLegacyDNMismatch. Inactive mailboxes with an auto-expanding archive can't be restored this way.
Common problems
- The mailbox isn't in the list: the 30 days have passed and there was no hold. Then the mailbox is gone. You might still recover deleted emails from other mailboxes involved.
- Several mailboxes with the same name: always work with the ExchangeGuid, never with the email address.
- The request stalls or fails: check the details with
Get-MailboxRestoreRequestStatistics -IncludeReport. With corrupt items, a new request with a higher-BadItemLimitsometimes helps. - The target mailbox is full: pick a shared mailbox or the archive as the target.
Alternatives
- Restore the user: within 30 days, restore the deleted user in the Microsoft 365 admin center under Users > Deleted users. Their mailbox comes back too, but they need a license again.
- Convert to a shared mailbox: when someone leaves, convert the mailbox to a shared mailbox first instead of deleting the user right away. Colleagues get access, and a shared mailbox up to 50 GB needs no license. Don't forget to set an out of office on the shared mailbox.
FAQ
Can I do this in the Exchange admin center?
No, restoring into another mailbox only works with PowerShell.
Does the deleted mailbox still exist after the restore?
Yes. A restore copies the content. The source stays soft-deleted until its retention period runs out.
Nederlandstalige versie: Verwijderde mailbox terugzetten in Exchange Online