What do you mean by Email Forwarding?
Basically email forwarding allows you to create a unique email account which will forward any incoming email to other email account(s).
In your control panel the email forwarding manager tool allows you to setup your email forwarding addresses.
When you receive an incoming email to an unique forwarding email address, the email is forwarded to the "Forward To Address(es)". The "Forward To Address" can use any of your domain's POP accounts or can be outside email accounts hosted elsewhere.
The unique forwarding email address cannot be the same as an existing POP account or Autoresponder username for your domain.