Reduce the Number of Undeliverable Mail Pieces

Undeliverable Mail

No one wants to receive stacks of undeliverable mail pieces. Not only does that stack represent a missed opportunity to make a sale, but it also represents wasted marketing dollars that could have been invested elsewhere. One of the main reasons mail pieces are undelivered is due to a lack of data hygiene.  

Data hygiene is an important process that needs to be run regularly. It can cover a variety of tasks, but we will look at some key steps that impact deliverability rates. 

Common Reasons for Undeliverable Mail: 

  1. Poor Address Formatting
  2. Incomplete Data
  3. Recipient No Longer at Address
  4. Deceased Recipient
  5. Data Entry Error
  6. Skewed Data Formatting
  7. False Information Included

How Data Hygiene Corrects Undeliverable Mail Issues: 

Poor Address Formatting

A crucial piece of data hygiene processing is aligning data with what the United States Post Office has on record. The step is commonly referred to as CASS or Coding Accuracy Support System. When you run a data file through CASS, it verifies the addresses you have with all known deliverable addresses in the United States and makes any necessary changes to increase the accuracy of your mailings. 

Incomplete Data 

Sometimes, data records are missing important information such as zip codes, names, etc. Data scientists will take your mailing list and append any data needed to complete the address and make the record mailable.   

Recipient No Longer at Address

Many of your recipients will move and change their address, and either it will take them a while to update their information with you, or they will forget. In fact, moves happen so frequently, that over the last 5 years, the United States Post Office processed an average of 35.5 million addresses a year.  

You can combat this issue by running a data hygiene step called NCOA or National Change of Address. Data Scientists will run your list through the USPS database and update any records that have a new address. This will help you stay in touch with your audience.  

Deceased Recipient

When an individual on your mail list passes away, it can be painful for the family to receive mail intended for their deceased loved one. Deceased suppressions identifies which individuals need to be removed.  

Data Entry Error

Anytime data is entered, there is always a chance of the information being captured incorrectly or in the wrong field. Data hygiene steps will identify those instances and correct the typographical errors. 

Skewed Data Formatting 

If you are gathering data from multiple sources, the layout and formatting of the data files will be different. File A may separate out names into Column G: First Name and Column H: Last names while File B may combine them into Column I. These fields need to be uniformed in order to prepare the records for the mailing. Part of the data hygiene process is ensuring all data fields are mapped out correctly, so all data points are merged into one cohesive file.  

False Information Included

Occassionally, people will enter false information or profanity into forms they don’t want to fill out. Super data hygiene includes steps to identify and remove records containing profanity, so you’re not wasting money targeting made-up records.  


Data hygiene may seem tedious or not a critical need, but if you keep putting it off, you could be wasting thousands of dollars on sending undeliverable mail pieces. By incorporating this process into your direct mail campaigns, not only will you reduce your marketing waste, but you will also increase the accuracy of your response rates. This will let you know how well your campaigns are truly doing and have a better read on what you can do to continue improving results. 

Next Steps 

If you have a data list in need of cleaning, let’s connect. Our team of data scientists are experts at scrubbing lists and helping you increase response rates.