SMS Marketing in Klaviyo: How to Capture and Convert Leads
11 May 2025 · 3 min read
Stop asking for phone numbers on your main pop-up
Most ecommerce brands butcher SMS from the very first touchpoint. They launch a sign-up form and ask for an email address and a phone number at the same time, or they stick SMS on a mandatory second step right before revealing the discount code.
When you demand a mobile number on your primary sign-up form, your submission rate can drop by roughly 50%. You are introducing massive friction at the exact moment a shopper is ready to browse. The primary goal of your first pop-up is not to gather every piece of data under the sun. The goal is to get their email, deliver the discount code immediately on the success screen, and get that first purchase across the line.
If a visitor bails on step two because they do not want to give away their phone number, they never see the discount code. You lose the email lead, you lose the phone number, and you lose the immediate sale.
The 3-day delayed capture method
Instead of forcing SMS upfront, you should capture it with a dedicated secondary form shown only to existing email subscribers. This protects your primary list growth while steadily building your SMS audience.
Here is how I set this up in Klaviyo. Build a separate pop-up that exclusively targets visitors who have opted into email marketing but have not yet opted into SMS. To avoid annoying your newest subscribers, build a segment rule so this form only appears after a delay:
Condition: Has subscribed to email marketing.
Condition: Has subscribed to SMS zero times overall.
Condition: Has subscribed to list zero times in the last 3 days.
That 3-day buffer ensures a new subscriber has enough time to use their initial welcome voucher without getting bombarded by another pop-up on their next page view. It makes giving you their number an easy, low-pressure decision.
Two other places to collect SMS consent
A delayed pop-up is not your only option for list building. You can build a high-intent SMS list by tapping into two other high-converting touchpoints in the customer journey.
1. Shopify checkout opt-in
Ensure your checkout settings include an explicit SMS marketing opt-in checkbox. Shoppers at checkout already have their wallets out and are entering their phone numbers for shipping updates anyway. Ticking a marketing consent box here feels natural and carries very little friction.
2. A dedicated welcome flow email
Add an email into your automated welcome series (usually around email four or five) that asks subscribers if they prefer VIP text alerts. Link that email directly to a dedicated mobile-friendly landing page with an SMS opt-in form. You are offering a clear channel preference to people who are already reading your emails.
The reality of SMS costs outside the US
Here is the thing about SMS marketing: it is not cheap. If you are operating in the United States, SMS fees are relatively low. But for brands in Australia, New Zealand, and the UK, sending text messages in Klaviyo can get expensive quickly.
Because of higher per-carrier fees, you cannot treat SMS like email. You cannot send weekly newsletters, educational tips, or long brand stories over text. A standard SMS segment is strictly limited to 160 characters. You cannot teach anyone anything useful in 160 characters without burning multiple credits per recipient.
If you blast your entire list with low-intent updates, you will quickly destroy your return on investment.
The only three SMS campaigns worth sending
To keep your SMS channel wildly profitable, restrict your manual campaigns to high-urgency, high-value events. In my books, there are only three campaign types you should ever send over SMS:
Site-wide sales: Black Friday, Cyber Monday, Boxing Day, or flash 24-hour promotions where timing matters.
Major product restocks: Alerting buyers when an out-of-stock best-seller is finally available again.
New product releases: Giving your VIP list early access to a limited run drop before the general public.
That is it. If an update does not fit into one of those three buckets, send an email instead.
Final Thoughts
SMS is a high-impact channel when used with restraint. Protect your on-site conversion rates by keeping your primary pop-up email-only, delay your SMS asks by at least 3 days, and only send text campaigns when you have urgent news that drives immediate revenue.
Scale your SMS revenue with In-box
If you want to build a compliant, high-converting SMS strategy that works alongside your email automations to hit that $1M+ mark, explore our SMS campaigns service to see how we manage it for growing ecommerce brands.
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