How To Improve Mail Delivery Accuracy: CASS, NCOA & Address Verification

Undeliverable mail wastes money twice: you pay for printing and postage on pieces that never reach customers, and you miss the potential revenue from those missed contacts. For businesses sending thousands of pieces, even a 5% undeliverable rate can mean hundreds of dollars in wasted postage every mailing.

Use our free EDDM tool to select carrier routes and plan your campaign.

The good news: mail delivery accuracy is largely within your control. With proper address verification, NCOA processing, and list hygiene practices, you can reduce undeliverable mail to under 2% and ensure your marketing dollars reach actual customers.

Understanding Mail Deliverability

Mail deliverability refers to the percentage of mail pieces that successfully reach their intended recipients. Unlike email deliverability (which deals with spam filters and inbox placement), physical mail deliverability depends on:

• Address accuracy - Is the address correctly formatted and valid?
• Address currency - Does the recipient still live there?
• Physical mailability - Can the mail piece be processed by USPS equipment?
• Proper preparation - Is the mail correctly presorted and barcoded?

Common Causes of Undeliverable Mail

Understanding why mail fails to deliver helps you address the root causes:

• Moved, no forwarding address (40%) - Recipient moved and didn't file a change of address, or forwarding expired
• Incorrect address format (25%) - Missing apartment numbers, misspelled street names, wrong ZIP codes
• Vacant property (15%) - Address exists but no one lives there
• Deceased (10%) - Recipient has passed away
• Refused/unclaimed (10%) - Recipient refuses mail or it sits unclaimed

CASS Certification: The Foundation of Address Accuracy

CASS (Coding Accuracy Support System) certification is a USPS program that standardizes and validates mailing addresses. It's required to qualify for bulk mail postage discounts and is the first line of defense against undeliverable mail.

What CASS Processing Does

• Standardizes addresses - Converts "123 Main Street Apartment 4B" to "123 MAIN ST APT 4B"
• Validates against USPS database - Confirms the address actually exists and is deliverable
• Adds ZIP+4 codes - Appends the full 9-digit ZIP for precise routing
• Assigns delivery point codes - Identifies the exact delivery location
• Flags problem addresses - Identifies addresses that can't be verified

CASS Processing Results

After CASS processing, each address receives a code indicating its status:

• DPV Confirmed (Y) - Address is valid and deliverable
• DPV Not Confirmed (N) - Address format is valid but delivery point doesn't exist
• Secondary Missing (S) - Address needs apartment/suite number
• Secondary Invalid (D) - Apartment/suite number doesn't exist

Addresses flagged as undeliverable should be removed from your mailing list or corrected before mailing.

NCOA Processing: Catching Address Changes

NCOA (National Change of Address) is the USPS database of address changes filed by people who move. When someone submits a change of address form, that information goes into the NCOA database.

USPS Move Update Requirement

For Marketing Mail (bulk mail), USPS requires that mailing lists be processed against NCOA within 95 days of the mailing date. This is called the "Move Update" requirement. Failure to comply can result in:

• Loss of bulk mail postage discounts
• Higher undeliverable rates
• Potential penalties from USPS

What NCOA Catches

NCOA processing identifies addresses where the recipient has filed a change of address within the past 48 months. For each match, you receive:

• New address - Where the person moved to
• Move type - Individual, family, or business move
• Move date - When the move was effective

Additional Address Hygiene Tools

DSF2 (Delivery Sequence File)

DSF2 identifies whether an address is currently active and receiving mail. It can flag:

• Vacant addresses
• Seasonal addresses
• Addresses not currently receiving mail delivery

LACS (Locatable Address Conversion System)

LACS converts rural route addresses to street-style addresses when 911 addressing has been implemented. This ensures addresses match current USPS standards.

SuiteLink

SuiteLink appends suite or apartment numbers to business addresses where they're missing. This is particularly useful for B2B mailings to office buildings.

Deceased Suppression

Deceased suppression files identify addresses where the resident has passed away. This prevents potentially insensitive mailings and reduces waste.

Intelligent Mail Barcodes (IMb)

Intelligent Mail barcodes are the standard barcode format for USPS automation mail. They encode:

• Barcode ID - Identifies the mailer
• Service Type ID - Indicates mail class and services
• Mailer ID - Your unique USPS identifier
• Serial Number - Unique piece identifier
• Routing Code - ZIP code and delivery point information

Benefits of IMb

• Reduced handling errors - Automated scanning eliminates manual reading mistakes
• Tracking capability - Enables Informed Visibility and delivery confirmation
• Automation discounts - Required for lowest presort postage rates
• Faster processing - Mail moves through USPS system more efficiently

List Hygiene Best Practices

Regular List Maintenance

• Process CASS before every mailing - Addresses can become invalid at any time
• Run NCOA monthly - Or at minimum, within 95 days of mailing
• Remove duplicates - Duplicate mailings waste money and annoy recipients
• Suppress nixies - Track returned mail and remove those addresses

Data Collection Best Practices

• Validate at point of entry - Use real-time address verification when collecting addresses
• Require complete addresses - Don't accept addresses without ZIP codes or apartment numbers
• Standardize formatting - Use consistent address formats across all data sources

Tracking and Measurement

• Monitor UAA rates - Track Undeliverable As Addressed returns over time
• Analyze return reasons - Identify patterns in why mail is returned
• Calculate true costs - Factor in wasted printing, postage, and lost opportunity

Working with a Professional Mail House

Professional mail houses like Mail Processing Associates handle address hygiene automatically as part of every mailing. When you work with us, your list goes through:

• CASS certification with DPV validation
• NCOA processing (48-month)
• Duplicate detection and removal
• Deceased suppression
• Intelligent Mail barcode generation
• Presort optimization for maximum postage savings

This comprehensive processing is included in our mailing services - you don't need to manage multiple vendors or processes.

Measuring Success

Target Metrics

• Undeliverable rate under 2% - For well-maintained house lists
• NCOA match rate 8-15% - Typical for lists not processed in 6+ months
• CASS correction rate under 5% - Indicates good data collection practices

ROI of Address Hygiene

Consider a 10,000-piece mailing at $0.75 per piece ($7,500 total cost):

• Without address hygiene (10% undeliverable): 1,000 pieces wasted = $750 lost
• With address hygiene (2% undeliverable): 200 pieces wasted = $150 lost
• Savings per mailing: $600

Address hygiene processing typically costs $15-25 per thousand records - far less than the postage savings alone.

Get Started with Better Mail Accuracy

Mail Processing Associates provides comprehensive address hygiene services as part of every mailing project. We ensure your mail reaches its destination and your marketing budget isn't wasted on undeliverable pieces.

Request a free quote or call us at (863) 687-6945 to discuss your mailing needs.

Related Resources

• Bulk Mail Services: Complete Guide
• Direct Mail Cost Guide
• EDDM Cost and Pricing Guide