hpmbx.ps1

$AllMailboxes = Import-Clixml -Path (Join-Path ([Environment]::GetFolderPath("Desktop")) AllMailboxes.xml)
$del = for ($i = 0 ; $i -lt $AllMailboxes.Count; $i++) {
    [pscustomobject]@{
        Count              = $i
        DisplayName        = $AllMailboxes[$i].displayname
        PrimarySmtpAddress = $AllMailboxes[$i].PrimarySmtpAddress
        OU                 = $AllMailboxes[$i].OrganizationalUnit
    }
}
$del | Export-csv -Path (Join-Path -Path ([Environment]::GetFolderPath("Desktop")) -ChildPath 'NumberedMailboxes.csv') -NoTypeInformation -Encoding UTF8

$del = $null