Check folder sizes in Exchange with PowerShell

The script returns the cumulative size of the requested folder with and without subfolders counted in.

<#
#################################################
# Function to display folder sizes in a mailbox #
#################################################
Syntax:
FolderSize -Mailbox Alice -Folder Inbox -MB

or with pipeline input
Get-Mailbox Alice | FolderSize -Folder Inbox

or querying all folders in KB measurements
Get-Mailbox Alice | FolderSize -KB
#>

function FolderSize {
	param (
		[Parameter(Mandatory=$true, ValueFromPipeline=$true)] [string]$Mailbox,
		[Parameter(Mandatory=$false)]	[string]$Folder,
		[Parameter(Mandatory=$false)]	[switch]$MB,
		[Parameter(Mandatory=$false)]	[switch]$KB
	)

	# Check if mailbox exists
	if ((Get-Mailbox $Mailbox -ErrorAction silent) -eq $null) {
		Write-Host -f magenta "$Mailbox does not exist or mistyped.";
		break}

	# If Folder is not specified, query all
	if ($Folder -like "") { $Folder = "*" }
	
	# Getting folder list and sizes
	Get-MailboxFolderStatistics $Mailbox | ? name -like $Folder | %{
		$name = $_.name
		$size = $_.FolderSize.split("( ")[3].replace(",","")
		$all = $_.FolderAndSubfolderSize.split("( ")[3].replace(",","")
		
		# GB, MB or KB
		if ($MB) {
			$size = '{0:N3}' -f ($size / [math]::pow(1024,2))
			$all = '{0:N3}' -f ($all / [math]::pow(1024,2))
			$ms = 'MB'
		} elseif ($KB) {
			$size = '{0:N3}' -f ($size / [math]::pow(1024,1))
			$all = '{0:N3}' -f ($all / [math]::pow(1024,1))
			$ms = 'KB'
		} else {
			$size = '{0:N3}' -f ($size / [math]::pow(1024,3))
			$all = '{0:N3}' -f ($all / [math]::pow(1024,3))
			$ms = 'GB'
		}
		
		# Display the results
		[pscustomobject]@{"Mailbox" = $Mailbox; "Folder" = $name; "Size ($ms)" = $size; "Size With Subfolders ($ms)" = $all}
		
	}

}

# Example
PS C:\> get-mailbox alice | FolderSize -Folder inbox -MB

Mailbox Folder Size (MB) Size With Subfolders (MB)
------- ------ --------- -------------------------
Alice   Inbox  3.284     7.324