Postal Address Verification API


How do I use Postal Address Verification?

Postal Address Verification (PAV) is an API (Application Programming Interface). The API allows a business’s IT department to configure the Web Service on a web page, application or database with a few lines of code. There is no software to buy or install, no complex system to learn and the service’s data is automatically updated each month.

How fast is Postal Address Verification?

The API delivers address results in a fraction of a second.

How often do you update your database?

The PAV API receives updates from the USPS once a month.

Is there a way to get the address results in proper case instead of all caps?

Yes. This is done by using the “Return Case Sensitive” option in the VerifyAddressAdvanced operation. Please see the Proper Case section for details.

Do you cover Puerto Rico, Virgin Islands, Guam and military addresses?


Do you provide results for international addresses?

At this time the API fully validates only U.S. addresses. Canadian addresses are verified on a ZIP Code level.

Does Postal Address Verification return the name of the person associated with the address?

Names are included in the verification information for high-volume businesses or buildings only. Individual names are not included.

What is CASS Certification?

The Coding Accuracy Support System (CASS) is used by the USPS to evaluate the accuracy of address-matching software. For a product to be CASS™ Certified it must obtain a miniumum score of 98.5% correction accuracy for ZIP +4, Carrier Route, 5-digit and LACSLink® and 100% Delivery coding, DPV® and RDI™.

Do you provide rooftop accuracy with your geolocation information?

The API provides geolocation for USPS mailbox locations. If not available, the geolocation information defaults to the centralized point of the ZIP Code +4.

Does using this service help with postal discounts?

You can qualify for some postal discounts by using Intelligent Barcode information.

Do you return Census Information?

Yes, we do offer information such as Congressional Information for use in your applications.

What is the source of your data?

We obtain our address data from the USPS (United States Postal Service) and our census information from the United States Census Bureau. We are in constant communication with them to ensure our information is accurate and up to date.

How can I integrate PAV into my application/system?

The API can be consumed with any programming language that supports REST or SOAP. See our Quick Start Guides for implementation examples.

Do you validate and return information on P.O. Boxes?

The API does validate P.O. Box information, but no additional information is available.

Do you offer information on the type of building an address is?

Yes. The VerifyAddressAdvanced method returns building type information in the MailingIndustryInfo and MultipleMatches objects. The building info is available in the RecordTypeCode property.

Do you offer batch processing?

Yes, batch processing is available depending on the volume and your business needs. Please contact us for more details.

Do you provide multiple matches for addresses?

If the secondary information is incorrect or missing, when setting the MultipleMatches parameter to true in the VerifyAddressAdvanced method, we will attempt to return up to 10 matching addresses.

Can I install the PAV API locally?

Not at this time. Esendex offers this API as a web service call requiring some coding to consume the API. You can save returned results to a database, however, for your records.


API (Application Program Interface)

An interface which is used for accessing an application or a service from a piece of software.

CASS Certification

The Coding Accuracy Support System (CASS™) is used by the USPS to evaluate the accuracy of address-matching software. For a product to be CASS Certified™ it must obtain a miniumum score of 98.5% correction in accuracy for ZIP +4, Carrier Route, 5-digit and LACSLink® and 100% Delivery coding, DPV® and RDI™.

Delivery Point coding

The USPS assigns a two-digit Delivery Point (DP) code to each mailbox or location where mail is delivered. The combination of the DP and ZIP Code +4 provides a unique identifier for every deliverable address. DP digits are encoded in the POSTNET delivery point barcode (DPBC) or as part of the Intelligent Mail Barcode (IMB) which are both used for USPS automation discounts.


Delivery Point Validation (DPV) is a validation process that confirms the existence of a specific address (down to apartment/suite number) and whether it can be delivered to or not.


LACSLink is a system that matches addresses against a list of rural routes, highway routes and box number addresses that have been renumbered or renamed due to 911 address conversions. These conversions involve changing rural-style addresses to city-style for 911 emergency system implementation.

Proper Case

Formatting addresses in upper case is a USPS and Canada Post addressing recommendation for ease of automatic scanning and application of bar codes. We include this standardization as part of the PAV Web Service. PAV also provides an optional data return for U.S. addresses called ReturnCaseSensitive for changing the data from upper case to proper case.


Residential Delivery Indicator (RDI) identifies whether a given address is classified as a business or residential. Businesses can avoid residential delivery surcharges by verifying delivery type status prior to shipping and identifying shipping patterns to improve operational efficiency.

Service Reference

A service reference (web reference) enables an application to consume one or more web services.


Provides improved business addressing information by appending known secondary (suite) information to business addresses.

Let’s start sending, together.