Most brands use SMS the same way they use a megaphone — blast the list, track revenue attributed, declare it a win.

What they're not measuring is what happens to customers who receive both SMS and email versus customers who only get one. That distinction turns out to matter a lot.

We found out the hard way — or rather, the data found it for us.

Linksoul is a golf apparel brand with a loyal customer base and a solid retention program. When we started working with them, they had email dialed in — strong flows, decent segmentation, consistent sends. SMS existed as a separate channel, mostly used for promos and product drops.

Standard setup. Most brands look exactly like this.

When we pulled segment-level LTV data from Klaviyo, we ran a comparison most brands never bother with: customers who received both SMS and email versus customers who only received email.

The customers receiving both spent over 2.5x more over their lifetime.

More than double.

We're not going to tell you this is a clean, controlled experiment. It isn't.

There are confounding factors. Customers who opt into SMS are self-selecting — they're likely already more engaged with the brand. Higher engagement probably correlates with higher LTV independent of the channel mix. We can't surgically isolate the SMS effect from the "more engaged customer" effect.

But here's what that caveat tells you: if your most engaged customers are the ones opting into SMS, and you're treating that channel like a broadcast tool, you're underserving your highest-value segment.

The causality question is less important than the strategic implication. These customers are raising their hand and saying I want more from you — and brands respond by sending them the same promo everyone else gets.

That's the mistake.

Broadcast SMS looks like:

These aren't useless. But they treat SMS as a cheaper, more intrusive version of email.

Retention SMS looks different:

The difference is whether SMS is a delivery mechanism or a relationship channel.

Most brands have it configured as the former. The LTV data suggests it should be the latter.

For Linksoul, the shift wasn't dramatic in terms of volume — it was about intent.

We stopped using SMS as a redundant send for email content and started using it for moments that email handles poorly: time-sensitive, personal, high-signal touchpoints. Think less "here's our newsletter in text form" and more "you bought this product three months ago — here's what pairs with it, and here's why it matters for your game."

We also started looking at SMS opt-in as a segmentation signal, not just a compliance checkbox. If someone opted into SMS, that told us something about their relationship with the brand — and we started treating them accordingly across both channels.

The LTV gap didn't close. It widened. Which means the brands that crack this channel mix early are building a durable advantage over brands still treating SMS like a megaphone.

If you're running SMS and email in parallel but not measuring LTV by channel combination, you're missing the most important retention insight available to you.

Pull the segment. Compare lifetime value for email-only vs. email + SMS subscribers. If the gap is significant — and it probably is — the question isn't whether to invest more in SMS. It's whether your SMS program is actually earning that investment or just capturing credit from customers who were going to spend more anyway.

The distinction between capturing credit and creating value is where most retention programs fail.

Fix the intent, and the numbers follow.

ps this is all we do at Bylders.io - the best retention marketing agency for direct to consumer brands to grow, profitably.