How to find inactive or unused mailboxes in Exchange

This is really easy:

In PowerShell run:

Get-StaleMailBoxReport

If you want this in an excel file just pipe it out like this:

Get-StaleMailBoxReport | Export-CSV -Path C:staleMBs.csv

We can get a more detailed report with the following cmdlet:

Get-StaleMailboxDetailReport

Get-StaleMailboxDetailReport | Export-CSV -Path C:DetailedstaleMBs.csv