There are two Foreach loops in PowerShell:
foreach ($i in $collection) { # do stuff with $i }
$collection | Foreach-Object { # do stuff with $_ }
You kind of have a mash of both, and I'm not quire sure what you're trying to achieve. I assume $customers is a collection you've declared elsewhere and you want to filter mailboxes to those included in it? If so, you don't even need a foreach as the pipeline is handling it for you:
import-csv -path "c:\storage\customer.csv |
Get-mailbox -resultsize unlimited |
where {$customers -contains $_.customattribute1} |
Get-Mailboxstatistics |
select displayname,TotalItemSize,ItemCount,@{expression={$_.totalitemsize.value.ToMB()};label="Size(MB)"} |
sort-object TotalItemSize |
out-file c:\report\$customer.txt
To use a foreach loop in this script you would replace your Where statement with
foreach-object { if ($customers -contains $_.customattribute1) { $_ } } |
This is saying to loop through each item, and if it's contained in $customers then send it on through the pipeline.
To be honest I've not had any opportunity to work with PowerShell and Exchange so I can't say much on piping a CSV to Get-Mailbox, I can only assume it works.
