If I have an Exchange 2000/2003 server located at a colo and another
Exchange Server 2000/2003 server located in my building, can Exchange
be configured so that any email that comes to my company, would hit the
first server and then forward a copy to the Exchange server that is
sitting in my building?  The users would have their default be the
Exchange Server at the building but if something were to go happen,
power outage etc, I could change their setting to point to the Exchange
server that is located at the colo and they could continue running with
access to all their email, etc?

I know there are other fault tolerant setup such as clustering etc but
some companies can't afford it.

And this is a company that provides some sort of technology for
Exchange and so when customers come in, they will see the compnay using
exchange with the product they sell.

Any information would be appreciated.