Mailbox database must not be overwritten by a restore.
Email system availability depends in part on best practices strategies for setting tuning configurations. Unauthorized or accidental restoration of mailbox data risks data loss or corruption. This setting controls whether the mailbox store can be overwritten by a backup, which will cause loss of all information added after the backup was created. It should only be enabled during maintenance windows or following an outage (immediately before a restore is to be made), and cleared again immediately afterwards. During production windows, this feature must be disabled.
Open the Exchange Management Shell and enter the following command:
<'MailboxDatabaseName'> -AllowFileRestore $false
Open the Exchange Management Shell and enter the following command: Get-MailboxDatabase| Select Name, Identity, AllowFileRestore If the value of 'AllowFileRestore' is not set to 'False', this is a finding.