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Understanding Address Verification

Written By Amber Breeden

March 4, 2022

The success of your direct mail campaign begins with one thing: deliverability. It doesn’t matter how beautiful the design is or how good the offer if that mailer never makes it into your customers’ hands. Bad address data is a waste of both time and money. That is why all of our direct mail projects, including automated campaigns using Banjo, go through address verification.

We verify all direct mail data through a process called CASS™, and most of the data also goes through a secondary process called NCOA. Those acronyms may or may not mean anything to you, but they matter a great deal when it comes to the quality of your mailing data and your deliverability rates. Let’s take a deep dive on each of these processes to understand the full address verification process.


Coding Accuracy Support System (CASS) is a certification system from the United States Postal Service (USPS) for address validation. CASS will standardize your mailing list, update outdated street addresses, and verify that addresses are valid and complete. It’s important to note that CASS only looks at the address field (including company)—it does not look at individual names. 

To ensure address deliverability, CASS uses SuiteLink®, DPV® and LACSLink®.

  • SuiteLink matches and appends known suite numbers to addresses of businesses in multiple-occupancy buildings. 
  • DPV, or Delivery Point Validation, verifies that an address is actually deliverable. 
  • LACS, Locatable Address Conversion System, matches addresses against a list of rural route, highway route, and box number addresses that have been renumbered or renamed and then updates the address accordingly. While similar to NCOA, which we’ll get into below, the LACS database is updated based on the implementation of emergency services.

In addition to these products, CASS also looks at mail carrier routes and the last four digits of a ZIP code to improve address accuracy. A correct address saves the Postal Service time, money and manpower by reducing the volume of 1) non-deliverable mail; 2) unsorted mail; 3) mail that is deliverable but requires extra effort to determine the proper location. 

Here’s an example of what CASS will correct in an address:

The input of:


Produces the output of:

REDMOND WA 98052-8300

Here, CASS corrects the misspellings in the street and city name; adds the street suffix, ZIP code and the last four digits of the ZIP; and, in this case, identifies the address as a business. Keep in mind that CASS is not a miracle worker. It does a good job fixing minor typos, but the input info has to be somewhat close to accurate for the system to catch and correct the typos.

In addition to address verification, CASS also returns descriptive information about the address (e.g., if it’s a business or residential address). If an address comes back as UAA (Undeliverable As Addressed), we’ll remove that record from the data and you’ll receive a file of all removed records. We recommend removing these addresses from your database or contacting those customers for updated, accurate address information. 

Something to consider: we do not remove “unverified” addresses (those missing the last four digits of the ZIP code), unless you request it. Depending on the rate of mail, you may not get back any undeliverable pieces. For example, USPS will not return or forward mail sent at the Standard/Nonprofit rate unless you use a USPS service endorsement (e.g., ADDRESS SERVICE REQUESTED). If a chunk of your direct mail is undeliverable and you aren’t able to track that, it could skew your overall response rate for the campaign because you would consider these individuals unresponsive when they never actually received the mail piece.


The other address verification tool we often use is NCOALink® (National Change of Address). NCOA is a product of the United States Postal Service and provides updated and accurate addresses for individuals, families, and businesses that have filed a “Change of Address” form at the Post Office when moving. NCOA will also indicate foreign moves and people who have moved with no forwarding address. There are approximately 160 million records in the NCOA database.

NCOA reduces undeliverable mail by comparing existing individuals or companies to an address and then updating the record to the most current address in the system. The NCOA database ensures that the addresses match the USPS formatting requirements. 

We often use NCOA for bulk mail, as it minimizes the number of UAA mail pieces, saving you money and reducing the USPS’s processing of this type of mail. NCOA is the preferred method to comply with the Move Update standard.

One important note on NCOA: updated address records only remain in the database for four years. So it’s important to use the COA reports you receive from your account or project manager to update the record in your database if you plan to continue mailing that person or business past that four-year mark. Read more about COA reports here.

There are a number of other address verification tools* you can take advantage of for even more reliable targeting, including but not limited to:

  • Address Resolution Service (ARS), which will do the detective work to correct undeliverable address data.
  • Proprietary Change of Address (PCOA), which finds and corrects addresses for people who have moved without filing a Change of Address form.
  • Track N Trace®, which offers intelligent mail tracking and reporting.

Contact us to learn more about More Vang can improve your direct mail deliverability and results for both single and automated campaigns.

*Other address verification tools are available for an additional fee.