Is there any way to intercept outgoing email sent from a specific account (mailbox) and forward a copy to another account/email? Any help would be appreciated.
Not on the server level, at least through the web panel. Support could technically do this for you, maybe, although I doubt they would.
Have you looked into a client-side solution? Many mail clients lets you specify a BCC for every message.
Actually, there's no way to do this (on a per-user or per-domain basis) with Postfix (as far as I'm aware). You'd have to look into either a client-side solution, or setup your own server (which may be more or less feasible depending on your situation).