Get-Mailbox -Identity $null
WARNING: By default, only the first 1000 items are returned. Use the ResultSize parameter to specify the number of items returned. To
return all items, specify "-ResultSize Unlimited". Be aware that, depending on the actual number of items, returning all items can
take a long time and consume a large amount of memory. Also, we don't recommend storing the results in a variable. Instead, pipe the
results to another task or script to perform batch changes.
...Nope, looks like I'm wrong on this one. For the sake of consistency this is exactly what *should* happen.