Forwarding Email Copy

need best solution for the following:

UserA has email address: nameA@ourdomain.com

UserB has email address: nameB@ourdomain.com

A is going to be the ?primary? warranty person with B as their backup. A ?new? email address is to be published to our client community as:service@ourdomain.com

What is the best way to get email coming in to this service email address to A with a copy to the backup user B above???