With the following command you can list all the mailboxes that are hidden from the GAL (Global Address List). A very usefull command when you’ve to perform a migration from Exchange to Exchange and you’ve pre-created the new Exchange mailboxes.
Get-Mailbox | Where {$_.HiddenFromAddressListsEnabled -eq $true} | ft -wrap
Get-Mailbox | Where {$_.HiddenFromAddressListsEnabled -eq $true} | Select Name, HiddenFromAddresslistsEnabled, ExchangeVersion
