This cmdlet displays forwarding information available on a collection of mailboxes. This includes forward to mailbox or contact (set by an administrator), forward to an SMTP address (set by a user or by administrator), or server-side forwarding rules (set in Outlook or OWA).
This information is commonly desired during audits and when planning Office 365 migration groups.
This cmdlet works both on-premises and in Office 365.
For Office 365, this cmdlet must be executed within a remote Office 365 session. For on-premises, the cmdlet must be executed in an Exchange Management Shell.
For more information see Display All Forwarding Information for Mailboxes in Exchange On-Premises and Off