Delete and re-create the default discovery mailbox in Exchange Online

You can use Exchange Online PowerShell to delete the default discovery mailbox, re-create it, and then assign permissions to it.

Why would I want to do this?

In Exchange Online, the maximum size of the default discovery mailbox is 50 GB. It's used to store In-Place eDiscovery search results. Before the size limit was changed, organizations could increase the storage quota to more than 50 GB. As a result, discovery mailboxes could grow to more than 50 GB. Discovery mailboxes that are larger than 50 GB are no longer supported.

How you resolve this issue depends on whether you want to save the search results from a default discovery mailbox that's exceeded 50 GB.



Do you want to save the search results? Do this
No Follow the steps in this topic to delete, and then re-create the default discovery mailbox.
Yes Follow the steps in Reduce the size of a discovery mailbox in Exchange.

Use Exchange Online PowerShell to delete and re-create the default discovery mailbox

Note

You can't use the Exchange admin center (EAC) because discovery mailboxes aren't displayed in the EAC.

  1. Run the following command to delete the default discovery mailbox.

    Remove-Mailbox "DiscoverySearchMailbox{D919BA05-46A6-415f-80AD-7E09334BB852}"
    
  2. In the message asking you to confirm that you want to delete the mailbox and the corresponding Active Directory user object, type Y, and then press Enter.

    A new user object is created in Active Directory when you create the discovery mailbox in the next step.

  3. Run the following command to re-create the default discovery mailbox.

    New-Mailbox -Name "DiscoverySearchMailbox{D919BA05-46A6-415f-80AD-7E09334BB852}" -Alias "DiscoverySearchMailbox{D919BA05-46A6-415f-80AD-7E09334BB852}" -DisplayName "Discovery Search Mailbox" -Discovery
    
  4. Run the following command to assign the Discovery Management role group permissions to open the default discovery mailbox and view search results.

    Add-MailboxPermission "DiscoverySearchMailbox{D919BA05-46A6-415f-80AD-7E09334BB852}" -User "Discovery Management" -AccessRights FullAccess -InheritanceType all