New-MailboxExportRequest -Mailbox username -FilePath \\server\share\file.pst
Get-MailboxExportRequest
Get-MailboxExportRequest -Name MailboxExport | fl
Get-MailboxExportRequest | Get-MailboxExportRequestStatistics
Get-MailboxExportRequest | where {$_.status -eq "Completed"}
Get-MailboxExportRequest | where {$_.status -eq "Completed"} | Remove-MailboxExportRequest