What would be the best way to modify an incoming sender address so that messages from any account on a certain domain (user1@mycompany.com, user2@mycompany.com, etc) appear to the user as a single address (singleuser@mycompany.com)?

What I have is a paging service that sends messages to us from a variety of addresses (which seem to be created on the fly) at their specific domain. I want to have a filter or listener domain mapping that will have all of those addresses appear to be coming from one address.

Thanks,

Chris