Frequently asked questions about ZP4

  1. What is ZP4?
  2. How can ZP4 help me?
  3. How does ZP4 work?
  4. What are carrier route numbers?
  5. Does ZP4 print mailing labels and barcodes?
  6. Will ZP4 find duplicates in my address list?
  7. What's the best database or program for maintaining address lists?
  8. How long does it take to automatically process my address list?
  9. How many addresses can I process?
  10. What if I don't want to reveal the addresses I'm scrubbing?
  11. Can my programs directly access the ZP4 database files?
  12. Does the ZP4 database include personal names with addresses?
  13. What if my address lists contain errors?
  14. How long has ZP4 been available?
  15. Is ZP4 CASS Certified™? What is CASS™?
  16. How often is ZP4 updated?
  17. How often do I have to update my addresses?
  18. What are DPV®, LACSLink®, SuiteLink™, eLOT®, and Geo?
  19. Can ZP4 distinguish between residence and business addresses?
  20. Can I use ZP4 on more than one computer?
  21. Can I let people access ZP4 via my web site?
  22. Can I include ZP4 processing in a product I am selling?
  23. Can I use ZP4 to process data for my clients or to produce data or services?
  24. What platforms does ZP4 run on?
  25. How do I order ZP4 and what does it cost?
  26. How quickly will my order be processed?
  27. What if I have a question not answered above?

1. What is ZP4? ZP4 is software and official United States Postal Service® databases that together provide a powerful tool for automatically determining the correct mailing address, ZIP + 4® code, and mail carrier route number for any location in the United States.

2. How can ZP4 help me? ZP4 adds ZIP + 4 codes and mail carrier route numbers to your address files so you can qualify for bulk mail postage discounts and pay much less postage to send your mail. ZP4 will also correct and standardize addresses, so you can confirm and validate addresses, avoid undeliverable addresses, and easily find duplicates within your list.

3. How does ZP4 work? ZP4 can be used three different ways:

In batch mode, ZP4 can process a database of any size, automatically correcting and standardizing every address in the file. ZP4 can process address lists in dBase, Access, Excel, FileMaker, Oracle, SQL Server, fixed-field text, delimited text, and other file formats.

Any program can also pass addresses directly to ZP4's interface, and ZP4 will pass the corrected and standardized address records back to the program, so any database or application can be given built-in interactive address correction capabilities. ZP4 includes templates and demo programs with source code showing how to send and receive address records from a variety of popular programming environments, including C, C#, Delphi, and Visual Basic.

ZP4 also provides an excellent user interface. To manually find an individual address, just type in a name to make ZP4 instantly find a city or street. Or, click on a state listed in ZP4's first window, and ZP4 immediately displays all the state's cities in an adjacent window. Click on a city, and ZP4 instantly lists every street in that city. Click on a street, and ZP4 displays the house number ranges, apartment number ranges, ZIP + 4 codes, and carrier route numbers for that street.

4. What are carrier route numbers? Carrier route numbers identify the route each mail carrier follows when delivering mail. Using carrier route numbers allows you to send mail at rates even lower than barcoded ZIP + 4 rates, although you must have ten or more pieces to the same carrier route number for the pieces to qualify for that rate.

5. Does ZP4 print mailing labels and barcodes? Yes, ZP4 includes the necessary software for sorting and printing barcoded First Class Automation letters and postcards or Standard Automation letters, including the generation of the required forms and reports so your mail qualifies for certain bulk mail discounts. ZP4 also includes a barcode font that can be used by any database or application program to print a postal barcode. Once ZP4 has coded an address, a postal barcode can be output by any program by using the barcode font.

6. Will ZP4 find duplicates in my address list? Yes, ZP4 includes "duplicate detector" tools for finding and marking or deleting duplicates within an address list. Note that once you use ZP4 to scrub your address list, non-standard addresses are automatically converted to the same form (for example, BOX 1, P.O. Box 1, and Post Ofc Box 1 all become the preferred PO BOX 1), and just about any database can then easily find duplicates.

7. What's the best database or program for maintaining address lists? Our customers use many, many different brands of software for maintaining their address lists, and each customer has different reasons for preferring the system they use. ZP4 is designed to be a convenient address correction tool regardless of where an address list is actually stored.

8. How long does it take to automatically process my address list? Processing speed mostly depends on the transmission time between your computer and ZP4 servers. However, ZP4 minimizes latency by processing bursts of compressed addresses and can also make multiple simultaneous connections for overlapped processing. The standard benchmark for ZP4's fastest correction tool is to process one million addresses in ten minutes on a relatively slow one megabit per second connection.

9. How many addresses can I process? You can process any quantity at any frequency, as fast as your network will allow. There are no caps or limits.

10. What if I don't want to reveal the addresses I'm scrubbing? ZP4 clients only transmit mailing addresses, and all such possible addresses are already known on ZP4 servers. Any other data in your records such as names or phone numbers are never included in transactions. Company names can be included for the best matching but aren't required. All transmissions with ZP4 servers are encrypted.

11. Can my programs directly access the ZP4 database files? Your applications can access arbitrary ZIP + 4 database records through ZP4's programming interfaces. ZP4 can also export any city, state, or ZIP Code range of the ZIP + 4 database to an uncompressed tab-separated text file, if you want to directly manipulate the data yourself. DPV, LACSLink, SuiteLink, and RDI databases are kept encrypted by the Postal Service™ and aren't exportable. There's lots of data, and searching it can be extremely complicated because of the way the Postal Service organizes address records. It's usually easiest to let ZP4 do the job of processing addresses, either my using standard ZP4 tools or by calling ZP4's interface.

12. Does the ZP4 database include personal names with addresses? No. ZP4 is not a list of addresses, but a tool to correct existing lists of mailing addresses. Many individual addresses are listed in the ZP4 database, but most of the records identify groups of low and high house numbers, or low and high apartment numbers, because if an address is within a given range, the corresponding ZIP + 4 code can then be determined. Individual building addresses are usually identified when the building contains apartments or commercial suites. Personal names are never identified. However, ZP4 does list individual addresses, including company names, for organizations that have been assigned unique ZIP + 4 codes by the Postal Service. The DPV database can verify specific mailing addresses, but is encrypted by the Postal Service to prevent using DPV as an address list.

If you're trying to acquire a list of addresses, search the Internet for vendors who sell address lists and mailing lists. Once you have a list of addresses, you can use ZP4 to validate, scrub, and standardize your list.

13. What if my address lists contain errors? ZP4 will detect all address errors and automatically correct most of them, including spelling errors and dozens of other kinds of errors. For any address that can't be automatically corrected, ZP4 will assign applicable error codes, which can be saved in the database you're updating.

14. How long has ZP4 been available? The first version of ZP4 began shipping in 1990. ZP4 superseded carrier route and five-digit ZIP® databases, which shipped in 1989, when Semaphore became a licensee of the Postal Service. Semaphore Corporation was founded in January 1982.

15. Is ZP4 CASS Certified? What is CASS? Yes, ZP4 is CASS Certified, and has been regularly recertified, ever since CASS regulations became mandatory in 1991.

CASS is the Postal Service certification program designed to improve the accuracy of ZIP + 4 codes, five-digit ZIP codes, and carrier route codes that appear on addresses. (Postal Service advertising guidelines do not allow vendors to reveal how the acronym "CASS" was derived, although the original unabbreviated phrase is still used in Domestic Mail Manual 708.3.1 and numerous other Postal Service documents.)

CASS Certified software are programs like ZP4 that have been tested and certified by the Postal Service CASS department as meeting their minimum requirements for "scrubbing", correcting, and validating address lists. CASS certification consists of a test: a large list of addresses of various types from around the country are selected by the Postal Service. The addresses may or may not have correct data fields (address, city, state, ZIP, and so on). The software being certified must match the address list to the ZIP + 4, DPV, LACSLink, and SuiteLink databases, and correct and standardize the various data fields. The corrected address list is then submitted to the Postal Service for scoring.

The Postal Service computes what percentage of the software's standardized output addresses are correct. To become CASS Certified, software must achieve a 98.5% or higher match rate for ZIP + 4 codes and carrier route numbers, and 100% for delivery point barcode extension numbers. (Although these percentages sound high, most addresses in a CASS test are easier to correct than typical addresses found in real mailing lists. For that reason, ZP4 also recognizes and corrects numerous additional common errors found in typical address lists, but not found in the CASS test and not properly corrected by other brands of "certified" software.)

Nowadays, the Postal Service considers the phrase CASS Certified addresses improper usage, and that people should instead say CASS processed addresses when discussing a list that has been corrected and standardized with CASS Certified software (because it's the software that's certified, and the list is then processed by the certified software). However, "CASS Certified addresses" has been widely used in the industry since long before the Postal Service began making the distinction, so it is now essentially a generic term.

ZP4 can automatically fill out and print CASS postal form 3553 when processing an address list, to document that your list has been processed with CASS Certified software. Form 3553 is required when obtaining certain bulk mail postage discounts.

16. How often is ZP4 updated? New editions of the ZP4 database are built from Postal Service files every month.

17. How often do I have to update my addresses? If you are declaring postage discounts, and you process your list with ZP4, that particular list will qualify for ZIP + 4 postage bulk rates for 180 days (or for carrier route discounts for 90 days) before having to be updated, but only if you freeze your address list and don't add, change, or delete any records.

In theory, you can clean your list, print CASS form 3553 to prove the list is certified, and mail for 180 days (or 90 days if using carrier routes) using the same CASS form for each mailing before you have to reprocess your list with ZP4 again to generate an updated form 3553, as long as you don't change any records in your list. In reality, you'll probably constantly add, change, and delete records (which obsoletes the CASS form), so you typically need to reprocess before each mailing in order to generate an accurate CASS form.

Per ZP4's license, you may sell or redistribute ZP4 data. However, you may not retain a copy of any data item for more than 30 days when repeatedly distributing or selling multiple copies of that data. Any data you sell or redistribute must be fetched anew at least every 30 days from ZP4 servers.

18. What are DPV, LACSLink, SuiteLink, eLOT, and Geo? DPV is a Postal Service database included with ZP4 and used to enhance address validation. Without DPV, ZP4 can only determine a candidate ZIP + 4 code for an address. With DPV, ZP4 can also determine whether the address is a valid location where mail is actually delivered. ZP4 is the first product ever certified by the Postal Service for DPV processing.

LACSLink is the Postal Service database that allows ZP4 to automatically perform conversions from one address style to another, typically from a rural-style box number to a street name (for example, RR 1 BOX 127A is converted to 17255 SCENIC RD). House and Post Office box renumbering and street renaming are also handled by LACSLink.

SuiteLink is the Postal Service database that allows ZP4 to add secondary (suite) address information to business addresses.

DPV, LACSLink, and SuiteLink (not just the ZIP + 4 database) are all be used to determine the proper CASS generated ZIP + 4 code for an address.

eLOT is a Postal Service database that allows ZP4 to automatically find line of travel numbers so mail qualifies for certain presort discounts.

Geo allows ZP4 to automatically determine the latitude and longitude, and Census Bureau tract and block numbers, for ZIP + 4 codes.

19. Can ZP4 distinguish between residence and business addresses? Yes. ZP4 includes the RDI database for determining if an address is a residence or a business.

20. Can I use ZP4 on more than one computer? Yes, you can install and use ZP4 on as many machines as you like, anywhere you like.

21. Can I let people access ZP4 via my web site? Yes.

22. Can I include ZP4 processing in a product I am selling? Yes.

23. Can I use ZP4 to process data for my clients or to produce data or services? Yes. You can also have the processing by any number of online client accounts be automatically reconciled from your master account.

24. What platforms does ZP4 run on? Windows. The only hardware requirement is a network connection.

25. How do I order ZP4 and what does it cost? You can order by paying with a credit card or check. ZP4 charges for the amount of input/output you use, at this rate.

26. How quickly will my order be processed? Allow 24 hours, but if your order is placed during our normal business hours, you'll typically receive ZP4 access the same day.

27. What if I have a question not answered above? First check the support page, otherwise contact Semaphore Corporation.


Go to the ZP4 home page.
Semaphore Corporation is a non-exclusive licensee of the United States Postal Service. The prices of Semaphore Corporation services are not established, controlled or approved by the Postal Service. The following trademarks are owned by the United States Postal Service: CASS, CASS Certified, DPV, eLOT, LACSLink, RDI, SuiteLink, ZIP, ZIP Code, ZIP + 4, Postal Service, and United States Postal Service. [DA#4.07]