Summary: Use Windows Powershell and the MSOnline cmdlets to identify all Internet domains attached to an Office 365 subscription.

 How can I use Windows PowerShell to easily audit an Office 365 subscription for domains that are attached to it?

 Use the Get-MSolDomain cmdlet, and if you want a list in a CSV file for auditing purposes, add
           the Export parameter, for example:

Get-MsolDomain | Export-CSV o365domains.csv