Technology concept: hex-code digital background

By GrayHair Software with insights from Adam Collinson and Josh McCaully

Data is one of the greatest tools in a marketer’s arsenal, but some metrics are easier to track than others. Email open and click-through rates are available at a glance in real-time and Facebook will neatly package your impressions and engagement on an easy-to-read dashboard. But then there’s direct mail, an often-bigger financial investment that even seasoned pros may not be optimizing to its full potential.

Most marketers are tracking the basic mail metrics – deliverability, response rates, and conversion, but this is just the highest level.


In our experience, deliverability is the very first thing mailers should be looking at. After all, you can’t achieve your campaign goals if that campaign never reaches the audience meant to see it.

Most people aren’t aware of the true scale of undelivered mail. Consider this: 36 billion pieces of mail are currently being tracked by the USPS®. Almost 4.9% of all marketing mail sent is marked undeliverable as addressed (UAA), though the reality is that much more goes unreported. Whether it’s human error, a lack of attention to address hygiene, or a combination of several factors, the fact is that an alarming percentage of your mail is not reaching its destination.

If you’ve purchased your mailing list, the number climbs even higher. On average, if you’ve bought a list, up to 8% of your mail may not be getting where it needs to go.

So where to start? With the data you already have. We’ve found that one in three deliverability issues can be prevented just by checking “the 3 Cs” of your lists:

  1. Are all addresses complete? One of the most common completion errors is leaving out the unit number of an apartment address, but many kinds of omissions can slip through the cracks without proper safeguards in place upon capture.
  2. Is each address correct? By this, we mean valid. Does the address exist and is it an address the USPS actively delivers mail to?
  3. Is it current? Poorly maintained lists will cost you in the long run, especially in a rental boom with home ownership at a historic low among young adults.

For most people, the analysis stops here and you’d already be well on your way to improving deliverability. But at GrayHair, we also encourage customers to evaluate whether an address is correct for your purpose.

Even if your purpose is simply to get mail delivered, are you filtering our complete, correct, and current addresses that are not valid for mail delivery? There are vast combinations of data and characteristics that indicate various levels of mail deliverability issues with an address. There are also industry specific regulations that may restrict the use of addresses that do not represent where the person actually resides.

POBoxesFor example, multiple industries have restrictions on the use of non-physical addresses – meaning an address that is not where the person actually resides. The most common type of non-physical addresses are P.O. Boxes, and they represent nearly 5% of the files in any given database.

Adding more confusion to the mix, P.O. Box™ Street Addresses (PBSAs) are specifically designed to look like physical addresses. It is common to find that 11% of mailpieces are made up of some type of address that does not represent where the person actually lives, but where they receive mail. Weeding out these types of addresses can be tedious, but ultimately cost saving.

Many marketing variables are outside of your control, but when it comes to reducing UAA mail, most of the answers are waiting in the data you already have.


Most marketers are tracking at least their response rates, but what are you doing with that data once you have it? The majority of mailers will evaluate the basics, like which content received the greatest response, but plenty of smaller characteristics slip through the cracks. For instance:

  • Who did you send it to? We’ve said it before, and we’ll say it again – it all comes back to your lists. Did you get a better response from new or current customers? If you purchased lists from various list providers, did one group outperform the others? Consider the source, not just the segment, when measuring success.
  • When did it arrive? Many mailers accept that delivery is in the USPS’ hands, and that’s that. But if you know that you consistently get more responses on certain days of the week, do everything in your power to plan and schedule accordingly. Create deadlines for content creation and printing and ensure that they are followed by all. Experiment with what works for you, and if a variable is within your control, control it.
  • Who isn’t responding? We’re quick to group respondents by what they have in common, but you can also draw connections between recipients who did not. Upon deeper analysis, you may find that your content – or your product – is not resonating with specific demographics. When working with large and diverse lists, keep the criteria broad enough to draw reasonable connections between locations, ages, or income level. If your list was carefully segmented, you can then begin to dig deeper into minutiae. Finally, look at historical data. If a customer has never once used a coupon that you’ve mailed them, it may be time to engage them another way.
  • What were the address characteristics? There are dozens of different address characteristics with dozens of potential values leading to thousands of possible combinations. What combinations yielded the highest and lowest response rates? In many campaigns, the pool of available names/addresses is larger than the volume of mail to be included in the mailing.  Replacing addresses with the lower performing characteristics with addresses with the higher performing characteristics will increase the overall ROI of your campaigns.

These variables may seem small on their own, but together, they can add up to big changes.


At the end of the day, whether you’re sending out a marketing piece or a statement, one thing matters: did the receiver take the action you wanted them to take? The answer is not always so simple, because sometimes what you believe to be a conversion issue is actually an attribution issue.

If you are following best practices, you’re tracking offer codes and phone numbers to confirm whether customers are coming to you through a mailing, but there’s more that you can be doing to clarify attribution.

  • Assess timing: A customer’s final touchpoint is seldom their only touchpoint. If a customer clicks “buy” in an email, but you can determine they received a promotional mailing earlier in the week, it may be foolish to write it off as a coincidence.
  • Check your traffic source: A big boost in direct traffic – customers coming straight to your website vs. through search, social, or email – could be a good indication that they saw your recent mailing.
  • Surveys: Customers have come to expect brief questioning about their experience with your brand – including how they first learned about you. A survey does not have to be a big or expensive undertaking; there are plenty of free websites that will get the job done.
  • Incentivize customers: If you’re offering a customer the same promotion online that you sent in a mailing, they’re likely to go with the easier option. Offering a slightly steeper discount with your print coupon is a great way to ensure they use the offer code you’re looking for.

It can be tempting to shy away from analytics because of their complexity. But if you start small with the data that’s already available to you, you could see a meaningful impact on deliverability, response rates, and conversion.

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