Quick summary
To add SMS cart recovery to a Shopify store, use a PECR-compliant platform (SMSBump, Postscript, or Klaviyo SMS), get explicit marketing consent at checkout, send a single recovery message within one hour of abandonment, and keep it under 160 characters with a direct link back to the cart. SMS cart recovery typically achieves 15-25% higher open rates than email.
You have an abandoned cart email flow set up. It is doing something, but you know a chunk of those carts are going cold before your second email even lands. Some of your customers barely check their email. They are on their phone, they see texts, and a well-timed SMS from your store would pull them back immediately.
The issue most Shopify merchants face is not knowing where to start with SMS: what is legal, which platform to use, how many messages to send, and whether to include a discount. This guide covers all of it.
Why does SMS outperform email for cart recovery?
The headline number is 98%. That is the average open rate for SMS messages, compared to approximately 20% for marketing emails. But open rate alone does not tell the full story.
The more useful metric is click-through rate. For abandoned cart SMS, click-through rates typically run between 10 and 20%, compared to 3 to 5% for abandoned cart emails. When someone opens an SMS and sees a direct link back to their cart, the friction to clicking is minimal. There is no inbox, no preview pane, no competing subject lines.
For UK merchants, Klaviyo's data shows that SMS cart recovery messages convert at 2 to 5 times the rate of a standalone email, when sent within 15 to 30 minutes of abandonment. The combination of both channels (email plus SMS) outperforms either channel used alone.
SMS is not a replacement for email recovery. It is an additional layer, typically used for high-intent abandoners who gave you their mobile number during checkout.
What are the legal requirements for SMS marketing in the UK?
UK SMS marketing is governed by PECR (Privacy and Electronic Communications Regulations) and the UK GDPR. The rules are stricter than for email, and non-compliance carries real risk. The ICO can fine businesses up to £500,000 for PECR breaches.
The key requirements:
- Explicit opt-in is required. You cannot send marketing SMS to someone simply because they gave you their phone number during checkout. You need a clear, affirmative opt-in: a checkbox (unchecked by default) with clear language stating they are consenting to receive marketing texts from your store.
- You must identify yourself. Every SMS must clearly state who is sending it. "Hi from [Brand]" is legally required.
- Opt-out must be simple. Include a STOP instruction in every message. All SMS platforms handle this automatically, but verify it is in place.
- Keep records of consent. Store the date, source, and method of consent for each subscriber. Klaviyo and Postscript do this automatically.
Do not import a list of phone numbers from your existing customer database and start messaging them. Build your SMS list with explicit consent from day one. A smaller, compliant list will always outperform a large list built on grey-area practices.
Which SMS platform should you use on Shopify?
Three platforms dominate for Shopify merchants in the UK:
| Platform | Price (UK) | Klaviyo Integration | Key Strengths |
|---|---|---|---|
| Klaviyo SMS | Bundled with Klaviyo email plan; per-message charges apply | Native | Single platform for email + SMS; shared flow logic |
| Postscript | From $100/month + per-message costs | Direct Shopify integration | Deep Shopify data; strong compliance tools |
| Attentive | Custom pricing (enterprise-focused) | Strong | Advanced personalisation; best for high volume |
For most Shopify merchants already using Klaviyo for email, Klaviyo SMS is the obvious starting point. It uses the same flows, the same segments, and the same analytics dashboard. You can build a single abandoned cart flow that sends an email at 1 hour, an SMS at 2 hours, and a second email at 24 hours, all within one Klaviyo flow.
Postscript is worth considering if you are not already on Klaviyo, or if you want more granular SMS-specific reporting. Their compliance tooling for UK PECR is solid, and their support team understands the UK regulatory context.
Attentive is built for high-volume enterprise brands. If you are sending fewer than 10,000 SMS per month, the pricing structure makes less sense.
What is the right timing for abandoned cart SMS?
This is where most merchants get it wrong. They either send too fast (feels aggressive) or too slow (cart has gone cold).
The data points to a clear sweet spot:
- 15 minutes after abandonment outperforms 1 hour for SMS. Klaviyo's own benchmarks show a 20% higher conversion rate for 15-minute sends versus 60-minute sends.
- Do not send SMS at unsociable hours. Even if a cart was abandoned at midnight, send your SMS between 8am and 9pm. Most platforms let you set quiet hours automatically.
- If you are running email and SMS together, stagger them. A common sequence: email at 1 hour, SMS at 2 hours, email at 24 hours. The SMS acts as a direct push for people who missed or ignored the first email.
A single SMS is usually sufficient for cart recovery. A two-message sequence (one at 15 to 30 minutes, one at 24 hours) can improve recovery rate modestly, but the second message has higher unsubscribe risk. Start with one message and test from there.
What should an abandoned cart SMS actually say?
SMS copy has hard constraints. You are working with 160 characters per message segment. Every word must earn its place.
The structure that consistently performs:
- Brand identification
- Specific reference to what they left (product name if possible)
- Clear link back to cart
- STOP opt-out instruction
Example: "Hi [name], you left [Product Name] in your cart at [Brand]. Complete your order here: [short link]. Reply STOP to unsubscribe."
Keep the link short. Use a tracked short link (Klaviyo generates these automatically) so you can measure click-through rates accurately.
On including a discount in SMS: this is the most common question. The evidence leans toward not including a discount in your first SMS. Customers who were going to buy anyway will use the code and eat into your margin. Reserve discounts for a second SMS or follow-up email if the first message did not convert. If you do use a discount, make it time-limited: "10% off your cart, valid for 24 hours."
How do you measure SMS cart recovery performance?
Track these metrics in Klaviyo or your SMS platform:
| Metric | What it tells you | Target |
|---|---|---|
| SMS delivery rate | Whether your numbers are valid and sending correctly | 95%+ |
| Click-through rate | Whether the message is compelling enough to drive action | 10 to 20% |
| Conversion rate (from click) | Whether the landing page converts | 20 to 40% |
| Revenue per SMS sent | Overall channel efficiency | Varies by AOV |
| Unsubscribe rate | Whether frequency or content is causing opt-outs | Under 2% |
Compare your SMS recovery rate directly against your email recovery rate using the same time window. The most useful benchmark: what percentage of abandoned carts does each channel recover in the first 24 hours? SMS typically recovers 3 to 8% of carts sent to (for opted-in contacts), compared to 2 to 5% for email to the same audience.
The real win is the combined rate when you run both channels together.
Key actions to take now
- Audit your Shopify checkout to confirm you have a clear, unchecked SMS opt-in checkbox with explicit consent language.
- If you are already on Klaviyo, activate Klaviyo SMS and add an SMS step to your existing abandoned cart flow (set to send 15 to 30 minutes after abandonment).
- Set quiet hours in your SMS platform to prevent sends between 9pm and 8am.
- Write your first SMS message: keep it under 160 characters, include your brand name, a specific reference to the cart, and a tracked link.
- Do not include a discount in your first SMS. Test a no-discount message for 30 days, then run an A/B test with a time-limited code.
- Set up a weekly report tracking SMS click-through rate, conversion rate, and revenue per recipient alongside your email equivalent metrics.
Frequently Asked Questions
Can I send SMS to customers who gave me their phone number at checkout but did not explicitly tick an SMS marketing box? No. Under UK PECR, a phone number collected for order confirmation and delivery updates cannot be used for marketing SMS without a separate, explicit marketing consent. Sending to these contacts puts you in breach of PECR. Build your SMS list through a clearly worded opt-in at checkout.
What happens if a customer replies STOP? They are immediately removed from your SMS marketing list. This is handled automatically by all major SMS platforms. You must not send them further marketing texts unless they re-subscribe. Order-related transactional SMS (dispatch notifications, for example) can still be sent as long as they were not also opted out of those separately.
Is SMS worth it for low-AOV stores? SMS has per-message costs (typically 3 to 10p per message in the UK depending on platform and volume). For stores with an AOV below £20, the margin on recovered carts is tight. Run the numbers: if your conversion rate on SMS is 5% and your AOV is £20, every 100 SMS sends recovers 5 orders at £20 each (£100 revenue). At 5p per message, your 100 messages cost £5. That is a positive return. Model it for your own figures before deciding.
Do I need a dedicated shortcode or can I use a shared number? For UK merchants starting out, a shared shortcode or a dedicated long number (a standard UK mobile number assigned to your brand) is sufficient. Dedicated shortcodes are expensive and largely unnecessary unless you are at very high volume. Klaviyo and Postscript both offer dedicated numbers as part of their setup.