---
title: "What is CASS?"
description: "CASS is the USPS certification for address-matching software. DPV checks delivery-point records, and neither one confirms who works at the address."
canonical: https://trysincerely.com/glossary/cass
last_updated: 2026-09-18
---
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# What is CASS?

> CASS is the USPS certification for address-matching software. DPV checks delivery-point records, and neither one confirms who works at the address.

Source: https://trysincerely.com/glossary/cass

CASS stands for Coding Accuracy Support System. It is a [USPS certification for address-matching software](https://postalpro.usps.com/certifications/cass), covering standardized addresses and postal coding. Certified processing includes delivery-point checks, but certification describes the software. The [DPV result](https://postalpro.usps.com/address-quality/dpv) tells you whether an individual address appears in the USPS delivery-point file.

Neither CASS certification nor a passing DPV result confirms that a person lives or works there. [NCOA](https://trysincerely.com/glossary/ncoa) checks filed changes of address, so it can identify a reported move. An absent move record does not establish current occupancy.

## Why it matters

Bad addresses are the silent tax on direct mail. Every undeliverable piece costs you the full print and postage price and returns nothing. Address processing can reduce that waste: typos get corrected, missing suite numbers get flagged, and fake or incomplete addresses get rejected instead of printed.

CASS-certified processing is one requirement for automation postage prices. USPS rules say any mailing claimed at an automation price must be produced from address lists matched and coded with CASS-certified methods ([DMM 602.9.1.2](https://pe.usps.com/text/dmm300/602.htm)), because clean ZIP+4 codes let their machines route mail without human handling.

For US B2B mail, postal checks are only part of the work. A CRM record often has a company name and city but no street address, or a headquarters address when your contact sits in a branch office. Verifying a wrong-but-real address still wastes the piece. You need [address resolution](https://trysincerely.com/glossary/address-resolution) first, then postal verification and review, to assess [mailability](https://trysincerely.com/glossary/mailability).

## Example

For example, software may standardize a street abbreviation and append a ZIP+4. Check the separate delivery-point result before treating that formatted address as usable. A missing or unconfirmed suite still needs review.

Sincerely includes address checks on every plan. US addresses use USPS delivery-point checks; Canadian addresses use Canada Post verification. Addresses must pass mailability checks before printing.

A postal check can confirm a delivery point. It cannot confirm the intended recipient is there or will read the piece.

## Related questions

- [CASS, NCOA, and address verification, explained](https://trysincerely.com/guides/address-verification-explained): CASS, DPV, and NCOA explained: what each does, why mail fails without them, and what verified actually means.
- [What is NCOA?](https://trysincerely.com/glossary/ncoa): NCOA is the USPS database of change-of-address filings, used to update a mailing list before mail goes out so pieces follow the people who moved.
- [What is mailability?](https://trysincerely.com/glossary/mailability): Mailability checks whether a recipient can receive mail at a verified address and whether the sender has legal permission to mail them.

---

Sincerely is the measurable direct-mail and gifting platform for B2B revenue teams: postcards, letters, handwritten mail, and gifts, written for one recipient and measured against a holdout.

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