RDI Services for Residential vs Business addresses... suggestions?

I'm working on a project that requires the use of an RDI (residential
delivery indicator) web service on the IBMi.

I see the USPS doesn't provide the APIs.. instead you need to use a
qualified vendor.

We don't want to use it for saving money on deliveries, but instead to go
through a mailing list database and distinguish between residential and
business address (this project we only want the business addresses, not the
home offices).

Preferably XML or JSON (or the option of both) for sending and receiving
would be the best option. We just want to send an address to the service
and receive if it's residential or business address.

Thanks!

Brad
www.bvstools.com