The DPV database is included on the ZP4 DVD-ROM to allow enhanced address validation beyond what's possible when only the ZIP + 4® database is used.
Without DPV, the ZIP + 4 database is only capable of confirming whether addresses fall within the "low to high" address ranges specified in ZIP + 4 records. For example, "100 to 198 (even) MAPLE AVE" is a typical house number range listed in the ZIP + 4 database, and any even house number in that range will match that ZIP + 4 record, whether or not the address is a valid Postal Service delivery point.
With DPV, ZP4 can confirm whether any individual address is a valid delivery point, regardless of what the ZIP + 4 database range implies. For example, only three addresses might actually exist in a given range like "100 to 198 (even)". Using DPV, ZP4 will validate the three known addresses and reject any other address in the range.
In other words, with just a ZIP + 4 database, you can only determine a candidate ZIP + 4 for an address. But since the ZP4 product includes both ZIP + 4 and DPV databases, you can also determine whether the address is a valid delivery point and produce valid ZIP + 4 codes.
In addition to allowing ZP4 to return a "yes/no" indication for any specific mailing address, DPV also allows ZP4 to detect if an address is a Commercial Mail Receiving Agency (a "mail drop" that rents mail boxes), or if an address is vacant.
Although Postal Service licensing allows the use of ZP4 beyond the expiration date of the ZIP + 4 database (with certain restrictions), DPV lookups may not be performed after the expiration date of the DPV database.
Postal Service licensing prohibits using DPV for the manufacture of address lists, and also prohibits the DPV database being exported outside the United States. A "violation" will occur if ZP4 detects DPV is being used to generate address lists, and subsequent DPV output will be suppressed until a restart code is obtained from Semaphore Corporation to clear the violation. Violation monitoring and enforcement is a requirement of the Postal Service. Semaphore Corporation is required to notify the Postal Service of your name and address when you request a DPV restart code. If you repeatedly generate DPV violations, the Postal Service will prohibit you from continuing to use the DPV system.
In December 2001, ZP4 became the first product ever certified by the Postal Service for DPV processing. DPV, LACSLink®, and SuiteLink® are required to determine the proper CASS™ generated ZIP + 4 code for an address.
ZP4 is also the first product ever certified by the Postal Service for the super-fast DirectDPV form of delivery point validation.