New-MailboxImportRequest -FilePath \\server\share\file.pst -Mailbox uname
New-MailboxImportRequest -FilePath \\server\share\file.pst -Mailbox uname -TargetRootFolder "Old data"
Get-MailboxImportRequest
Get-MailboxImportRequest | Get-MailboxImportRequestStatistics
Get-MailboxImportRequest | where {$_.status -eq "Completed"} | Remove-MailboxImportRequest