You can forward inbound email to another email address using the Forwarding feature. If you have storage enabled on the mailbox that you are forwarding email from then a copy of the email will be delivered there, as well as a copy sent on to the email addresses that you specify.
To turn on email forwarding, login to your control panel and click Mailboxes.
Click on the mailbox you wish to setup a forwarding rule for.
Now click on Forwarding.
You will see that mail forwarding is currently disabled. To turn it on, you need to add some email addresses to forward to. Click Forward List.
Click Add Forwarding E-mail Addresses to enter the email addresses that you wish to forward all received email to - you can add multiple addresses if you wish.
Once you have added the first forwarding email then mail forwarding will be enabled automatically. If you wish to turn off forwarding without deleting the email addresses that you have entered (so that you can re-enable it at a later date) then return to the General tab and click Disable Forwarding.
It is possible to setup an email address without a mailbox that only forwards email to the forward list without. To do this simply create a new email address following this guide, but untick Create storage box to prevent a mailbox being created and tick Enable email forwarding to setup which email addresses to forward email to.
If you have an existing email address that you would like to do this to, edit the storage quota for the mailbox by following this guide.