Question:

I am setting up a development server where they test a proprietary app
before moving it to the production environment.

This app generates tons of emails for their subscribers. On the test
system, I want all emails to go to one mailbox on the local machine,
regardless of the the recipient address. This machine doesnt have Internet
connectivity. Should I set up some sort of complex route?

Answer:

A couple ways to do it:

virtusertable:

@local-domain.tld         catchall-account

or 

See cf/README: LUSER_RELAY.