Your company updates all their addresses through Coding Accuracy Support System (CASS) and NCOALink software on a monthly basis. The presort operation applies Full-Service Intelligent Mail barcodes to each piece. Still, every day, the US Postal Service (USPS) returns piles of pieces of mail back to your offices. It can be a frustrating routine.

Savvy managers know that the most tangible evidence of addressing errors in any mailing is the volume of return mail. Instead of treating return mail as a nuisance, managers should consider it another tool to improve their address list.

If a company has done an effective job with cleansing their addresses, then their return mail will be below one percent. However, if that company mails out 50,000 bills a day, that still means 500 will be returned each day — over 10,000 pieces will be returned in a month. That’s a lot of mail.

So, what should a company do? We recommend a multi-step approach:

Keep accurate measurements

Update moves first

Fix obvious errors

Use CASS, NCOALink, and Address Element Correction (AEC) for tougher problems

Turn off mail for repeat offenders


Metrics Provide Valuable Insight

Measurements are important to determine the effectiveness and efficiency of your address quality program. With return mail, you need to know more than just volumes. You also need to know what percentage of your outbound mail the return mail represents. Studies have shown that almost 2.5% of presorted, First-Class Mail is undeliverable as addressed. However, best-in-class operations achieve a one percent or lower percentage of return mail. Accurate, consistent metrics will demonstrate where your operations stands, and how corrective actions are improving the situation.

Metrics will also reveal if something has changed. If the normal count of return mail represents 0.5% of outbound mail, and it suddenly jumps to one percent, that’s an indication of a new problem. Mailers may consider checking their most recent Mailer Scorecard to look for potential issues. The scorecard could show that there were additional errors in the Move Update with a specific service provider.

Immediate attention should be given to pieces that have address update information attached. These are the easiest mistakes to fix. If a new address is provided, then the customer’s record should be modified. If the intended recipient has moved and left no address, then the customer should be contacted by alternate means (e.g., phone or email) to obtain the correct information.

The next target should be the returns with clearly marked errors – missing house number, no unit or apartment designated, incorrect ZIP Code, etc. The customers’ records should be searched for the correct information and the address then updated. If the information isn’t evident, then contact your customer.

Unfortunately, many of the Nixie codes provided on the yellow return labels aren’t helpful. The most common is “Undeliverable as Addressed” and has no additional information provided. These addresses should be processed through CASS and NCOALink software to identify possible reasons. These addresses may have already been processed through CASS before, but the errors were skipped over. With a smaller batch, more attention can be given to the errors.

An approach used by some mailers is to enter the address into an internet search engine. The results may include additional information, like an apartment number. By looking at the map, especially the “street view,” you might be able to have a clearer picture of the complete address or reveal that the address is a large building or empty lot.

For the pieces that still can’t be resolved, consider using the USPS AEC program. AEC is best described as “CASS Plus.” With input from the mailing industry, the USPS developed specialized programs that break down the elements of the address and perform a series of evaluations and comparisons. Through these logarithms, the AEC software is able to add missing elements and correct many errors that commercial software can’t resolve.

For the tougher addresses, mailers can request the “AEC II” service. Under this program, the addresses are sent to the local USPS delivery unit for resolution. The USPS is then able to tap into their proprietary Delivery Force Knowledge system. In other words, they ask the letter carriers responsible for that address for their help. That’s right, a human being with actual knowledge of the problem address – not software – corrects the list.

If the address can’t be fixed, and mail pieces keep being returned, then your company should consider stopping mailing to those customers. There are very complicated rules that vary by industry about when a company can turn off mail. However, in most cases, sending a notification by Certified Mail, and then retaining the returned mail piece, will meet the official obligations. Work with your legal department to identify the best policy for your company.

People will continue to move without notifying you or the USPS. Errors will be made when entering customers’ addresses. Return mail will always exist. That means every day, the process must be repeated. Measure; update known moves; fix errors; use CASS, NCOALink, and AEC; and then stop mailing.

By following these steps, successful companies have reduced return mail to below 0.5%. Those positive results only happen through constant attention and prompt action.

Physical mail remains a critical link to customers in an increasingly digital world. But mail pieces that are returned to your company add no value to the relationship. Use the returned pieces to improve your data and strengthen the link to your customers.

Mark M. Fallon is President & CEO of The Berkshire Company, a consulting firm specializing in mail and document processing strategies. You can contact him at, or visit his blogs at or

This article originally appeared in the January/February, 2020 issue of Mailing Systems Technology.