The User Forwarding address is an external email address which receives an email message instead of VPOP3 placing the message into user’s mailbox. This differs from an Assistant in that the message can be placed in the user’s mailbox as well as being sent to an Assistant.
You set the forwarding address on the User General Settings page by entering the forwarding address into the Forward To box.
The User Forwarding address can be useful if a user is going to be out of the office and wants to be able to receive their email at a remote site (or in their personal email account).
A user can also set their forwarding address through their Web Mail settings, or by an email command.