Activate Existing and Dormant Customers with Handwritten Mail

As an e-commerce entrepreneur, you want to keep activating your customers — both existing and dormant ones. Since inboxes are becoming increasingly crowded, it’s crucial to stand out. Handwritten cards provide a powerful alternative.

Even if customers have unsubscribed from emails, you’re still allowed to send them physical mail. And it pays off: when upselling to existing customers, we see an average conversion rate of 11%. When reactivating dormant customers (those who haven’t ordered for more than six months and have unsubscribed), the conversion averages 5.5%.

Customer Case: Detailrs & Writify

How a Handwritten Card Brought Customers Back with a ROAS of 4.18

About Detailrs

Detailrs is a webshop for car enthusiasts who expect more than a “quick clean.” They sell premium shampoos, coatings, brushes, and accessories for people who take their cars seriously.

Detailrs’ customers are loyal and critical. They value quality, but also a brand that sees them as people. That’s why, at Detailrs, it’s not just about products — it’s about how you approach people.

The Challenge

In the run-up to the Spring Wash Weeks, the Detailrs team noticed that a segment of their loyal customers had gone quiet. Customers who once ordered regularly had been inactive for months.

Some had unsubscribed from emails. Others had simply disappeared off the radar.

The tricky part: you can’t reach them anymore through the channel you usually rely on. No newsletter, no reminder, no offer.

So the question was:

How do you win those customers back if you can’t email them, and you want something more personal than yet another discount code?

The Approach

Together with Writify, Detailrs chose something surprisingly simple: a handwritten card. Not a digital reactivation campaign, but a tangible, personal message delivered right to the doorstep.

Target Groups

• 721 cards were sent to loyal customers with 2+ orders who were no longer receiving emails
• 488 cards were sent to customers who hadn’t purchased for 6–12 months

Content

Each card was carefully crafted in Detailrs’ tone of voice: friendly, human, and without sales jargon. It included a unique discount code that gave 10% off on top of the ongoing Spring Wash Weeks offers.

The cards were handwritten by Writify’s robotic arm, which writes with a real pen in natural handwriting — nearly indistinguishable from the real thing.

Timing

The cards were mailed on March 19 and 20, ensuring they landed just before the Spring Wash Weeks started on March 21. Perfect timing to be top-of-mind.

The Results

The campaign delivered immediate, tangible results:

Beyond these numbers, the results could be measured even further, as returning customers are 50%+ more likely to place another order.

But the effect went beyond metrics.

Customers responded spontaneously. They mentioned the card when ordering, sent thank-you emails, or expressed their appreciation. Not because of the discount — but because it felt like someone had genuinely thought of them.

And that’s exactly what sets it apart from a standard campaign.

Why It Worked

In a time when inboxes are overflowing and marketing messages blur together, something physical stands out.

• A handwritten card grabs attention because you almost never receive one anymore
• It feels personal, even if it’s smartly automated
• It fosters recognition, appreciation, and often: action

What Detailrs Did Next

Detailrs decided not to leave it at a one-off campaign. Handwritten cards are now part of the customer journey.

• Customers who order four times automatically receive a card with a small surprise
• This is integrated into existing flows via Klaviyo
• The result: communication that remains scalable and personal

9.4% of recipients placed a new order!

We don’t do this just to try something “nice.” We do it because it works, and because it fits the way we want to engage with our customers.

At Detailrs, we believe real contact goes further than a push notification. That’s why we sometimes simply send customers a card. Personal, genuine, and at exactly the right moment.

And it works: 9.4% of inactive customers placed a new order after receiving the card.