Email forwarding let's you forward email sent to an addresss to another address or multiple addresses. It allows you to look more professional by creating separate department addresses for a business and forwarding all of their emails to one or more other boxes which can then filter and organize based on those addresses. It allows you to forward mail to an external address at another host or ISP, it allows you to send copies of a message to multiple addresses, etc. It can also come in handy to forward mail to another person while you are on vacation.
Forwards are setup in Cpanel under Mail => Forwarders. Normally, a forward will just forward the message. Sometimes, though, it may retain a copy in the forwarded box. To avoid this, you can setup a forward for an email box that does not actually exist in your domain, one that you haven't created.
To forward to multiple addresses, use a comma to separate the addresses. ie mailbox1@mydomain.com,mailbox2@somedomain.com To force an email account you have created to keep a copy and forward a copy, set up a forwarder under Forwarders as mailbox1@mydomain.com>>>\mailbox1,mailbox2@wherever.com The backslash is what makes it work.