Unlike your postcard to Santa (still waiting on my gift by the way...), your direct mail strategy doesn't have to feel like you're throwing your letter to the wind.
Just like any marketing program, carefully tracking, measuring, and optimizing your impact will help grow your program with confidence.
One thing to keep in mind before we get into the weeds: we recommend waiting 4 to 6 weeks before drawing any conclusions on your direct mail performance. We know, that sounds like longer than your other marketing channels, and it is, for good reason .
The time it takes for mail to land, be seen, and for the recipient to take action is on average 14-17 days. So by the time the laggards convert, we’re a month out from send. By setting the program up right from the start, you’re already accomplishing the hardest part. Exploring optimizations from here is a walk in the park
How to track your impact
A holdout group is a portion of your audience that you intentionally do not mail. They're your control group.
You might be itching to mail every single customer who is eligible, but a holdout group helps you answer your key questions: was the postcard what drove the purchase? Or was it the season? Or the sale you were running anyway? As a marketer, you know how important these groups are, and here are our best practices for A/B testing with your holdout group:
- Split your segment into two groups
- Keep them as similar as possible (same segment, comparable size)
- After your window, compare purchase behavior within the two groups
What you're looking for: did the people who got the postcard buy more, more often, or at a higher value than those who didn't? That’s how you can tell your story.
Create a unique promo code exclusively for your direct mail campaign and assign it in PostPilot when setting up your send.
Simple logic: if someone uses that code, the postcard gets the credit.
A few things to keep in mind:
- Make it memorable. Think: WELCOME15, COMEBACK20.
- Don't reuse it across other channels. Use that big brain of yours to think about different discount codes: your attribution reporting will thank you.
- Check redemptions in both PostPilot and Klaviyo to make sure the numbers line up.
Give your direct mail its own destination. A QR code driving to a custom URL (think: yourbrand.com/welcome-back) lets you track traffic that came directly from your mailing and nothing else.
To make it work:
- Match the landing page messaging to your postcard copy exactly. Consistency between the two helps drive the overall narrative of your campaign.
- Set up UTM parameters so Klaviyo and your analytics tools can attribute the visit correctly.
- Don't link to the page anywhere else to help isolate the tactic from your other marketing activities.
Your Klaviyo attribution window is the timeframe you give a marketing touchpoint credit for a purchase that happens afterward.
For direct mail, we recommend 4 to 6 weeks. Unlike email (opened and acted on within hours, if you're lucky), a postcard sits on someone's counter. It might take a few weeks before they actually go buy something.
To make this work:
- Review your attribution in PostPilot
- Start your window from the delivery date, not the send date. PostPilot tracks when cards are delivered so you can be more precise on impact.
How to measure your impact
Once your window closes, here's what to look at.
This is the incremental revenue your mailing group generated compared to your holdout group.
Revenue from mailing group - revenue from holdout group = revenue lift.
This is the number that tells you what your direct mail actually drove. This level of precision helps you refine your strategy.
This is the increase in customers purchasing within your mailing group, again compared to your holdout group.
Customers who purchased in the mailing group - customers who purchased in holdout group = customer lift.
This is the incremental revenue your mailing group generated compared to your holdout group.
Revenue from mailing group - revenue from holdout group = revenue lift.
This is the number that tells you what your direct mail actually drove. This level of precision helps you refine your strategy.
This is the increase in customers purchasing within your mailing group, again compared to your holdout group.
Customers who purchased in the mailing group - customers who purchased in holdout group = customer lift.
How to Optimize Your Results
You've waited. You've measured. Now you get to do something with it. Two levers to pull: timing and offer.
Timing
PostPilot recommends anchoring your timing to what they call "time between orders" data. Every brand has a typical repurchase interval: a window where customers can reasonably be expected to buy again. If a customer usually buys every 60 days and hits day 65 without a purchase, you are perfectly primed for checking in.
A few timing frameworks worth testing:
- Repurchase interval trigger. Send when a customer exceeds their expected time between orders. You're meeting them where they are instead of guessing.
- Post-purchase follow-up. Send 30 to 120 days after a first purchase to drive the second order. KURU Footwear does this at 35 and 120 days and sees an 11.5x ROAS.
- Lapsed customer reactivation. Target customers who haven't purchased in 60+ days and are at risk of not coming back on their own.
- Seasonal sends. Layer direct mail onto your existing email calendar for BFCM, Q5, Valentine's Day. Especially powerful for reaching customers who've unsubscribed from email and can't see your offers anywhere else.
Offer
A blanket discount is fine as a starting point. But the highest-performing campaigns match the offer to the customer's situation.
Some offer types to test:
- Winback discount. A straightforward percentage or dollar off for a lapsed customer. PostPilot sees 4x+ ROAS on winback offers regularly.
- Cross-sell. After a first purchase, recommend the natural next product. Someone buys a blender, you offer blender accessories. Someone buys two of four items frequently bought together, you show them the rest.
- Replenishment reminder. For consumable products (supplements, skincare, food), trigger a postcard when someone is likely running low.
- VIP exclusive. For your highest-value customers, make the offer feel like it's actually for them. Something they can't get from your emails.
Things to A/B test:
- Discount amount (10% off vs. $15 off vs. free shipping)
- Offer framing (save vs. get vs. treat yourself)
- Whether a discount is even necessary (sometimes a well-timed postcard without one converts just as well)