Residential delivery index
for residence vs. business detection

The Postal Service™ RDI™ database allows ZP4 to determine if an address is a residence or a business. RDI is included on the ZP4 DVD-ROM.

RDI databases expire monthly. Once an RDI database expires, you must purchase a current ZP4 edition to continue performing RDI lookups.


Go to the ZP4 home page.
Semaphore Corporation is a non-exclusive licensee of the United States Postal Service®. The prices of Semaphore Corporation products are not established, controlled or approved by the Postal Service. The following trademarks are owned by the United States Postal Service: RDI, Postal Service, and United States Postal Service. [DA#4.07]