How Can Your E-commerce Brand Maximize List Growth with SMS Opt-ins?

Is your e-commerce store’s SMS list growing as fast as it should be? If you’re not seeing the subscriber numbers you want, your opt-in strategy might be holding you back from unlocking SMS as your highest-performing marketing channel.

Building a strong SMS list isn’t just about quantity but about quality and compliance, too. With SMS open rates at 98% (compared to email’s 20%), the potential ROI is massive… if you’re doing it right.

In this article, we’ll explore how effective SMS opt-in strategies drive list growth while staying compliant, with a special focus on innovative approaches like CashBack from Postscript that are changing the game for Shopify merchants.

An SMS opt-in message is the explicit permission a customer gives you to send them text messages for marketing or transactional purposes. Unlike email subscriptions, SMS marketing requires expressed written consent before you can legally start messaging customers.

This consent is mandated by regulations, such as the Telephone Consumer Protection Act (TCPA), and the industry guidelines from the CTIA. Without proper opt-in procedures, you risk hefty fines and damage to your brand reputation.

Opt-in SMS processes generally fall into two categories:

• Single opt-in: A customer provides their phone number and expresses consent in one step, often via an online form or at checkout.

• Double opt-in: After the initial opt-in, customers receive a confirmation message requiring them to reply “YES” or tap a link to confirm their subscription.

Double opt-in creates an additional verification step that ensures customers genuinely want to receive your messages, providing an extra layer of compliance protection. 

While it may result in slightly fewer subscribers initially, those subscribers tend to be more engaged and provide better results for your business in the long run.

Here’s why you should be using SMS opt-ins as part of your growth strategy today.

Text messages have a 98% open rate, with most being read within minutes of receipt. This makes SMS the most direct and immediate way to reach customers, but only if you’ve built a quality subscriber list through proper opt-in processes.

When customers explicitly opt in to your SMS program, they’re signaling genuine interest in your brand, making them more likely to engage with your promotional messages and convert.

Effective SMS opt-in strategies capture not only phone numbers but valuable data that enables segmentation and personalization. When customers opt in, you can collect information about their preferences, allowing you to tailor your SMS marketing campaigns to their specific interests.

This personalization leads to higher engagement rates and, ultimately, more revenue per subscriber. Segmented SMS messages consistently outperform broad-based campaigns in terms of conversion rates.

Customers who opt in to receive your text messages are inviting your brand into one of their most personal communication channels. This represents a significant opportunity to build loyalty through value-added content and exclusive offers.

By respecting this privilege with relevant, timely messaging, you transform your SMS subscriber list into a community of engaged advocates who not only purchase more frequently but also have higher lifetime values.

Wondering how to boost your SMS opt-in rates? Get started with these! 

One of the most effective places to grow your list is directly on your website. Strategic pop-ups and banners can capture visitors’ attention at optimal moments in their browsing journey.

For maximum effectiveness:

• Time pop-ups to appear after meaningful engagement (15-30 seconds on site)

• Use compelling copy that clearly states the benefits of opting in

• Include a strong value proposition (i.e., discounts, exclusive content, etc.)

• Keep forms simple by asking for a phone number and using clear consent language

• Test different designs and offers to optimize conversion rates

The checkout process presents a golden opportunity for SMS list growth. Customers who are already purchasing have demonstrated trust in your brand, making them prime candidates for your SMS program.

Effective checkout opt-ins:

• Use pre-checked boxes (where legally permitted) or prominent opt-in fields

• Clearly explain that message frequency varies and highlight the value of subscribing

• Mention data rates may apply and include opt-out instructions

• Reinforce that subscription is optional but worthwhile

SMS keywords provide a versatile way for customers to opt in through physical form marketing or offline touchpoints. A keyword is a specific word or phrase customers text to your number to initiate subscription.

For example: “Text SHOP to 12345 to receive 15% off your first order!”

Effective SMS keywords should be:

• Short and memorable

• Relevant to your brand or the specific offer

• Used consistently across marketing materials

• Set up to trigger an automatic confirmation message with required disclosures

Your social media followers are already interested in your brand, making them excellent prospects for SMS marketing. Create dedicated posts or stories highlighting the benefits of joining your SMS list.

Source: Investopedia

QR codes provide a frictionless way for customers to opt in from physical marketing materials:

• Place QR codes on packaging, in-store signage, business cards, and print advertisements

• Have the code direct to a mobile-optimized opt-in form

• Include a clear call-to-action explaining where the QR code leads

Offering something valuable in exchange for a phone number significantly boosts opt-in rates. Discounts, coupon codes, or cashback rewards provide extra incentives for users to opt in. However, traditional discounts and coupon codes usually cost brands more money than they bring in. CashBack from Postscript represents an innovative alternative, often resulting in a 31% increase in list growth.

With CashBack, shoppers can redeem their reward after a purchase as either cash or a gift card to your store, creating a powerful opportunity for both immediate and repeat purchases. 

Because CashBack is more profitable than standard coupon codes, brands can afford to offer bigger incentives that drive stronger results. Cashback offers drive a more engaging shopping experience and encourage repeat purchases with gift cards or store credit – a win-win for both brands and shoppers.

Testing both traditional discounts and CashBack incentives allows brands to determine which drives better ROI for their specific audience. However, we’ve seen that users are 2.5x more likely to pay full price for an item when using a gift card. We’ve also seen brands that test higher cashback rewards during peak sales seasons drive a higher AOV and even more repeat purchases, making cashback rewards a strong incentivized opt-in strategy. 

Compliance and customer consent are essential parts of SMS communication for brands. Here’s how you can make sure you’re on top of it.

Compliant SMS opt-ins require transparent disclosure of several key elements, so when customers sign up to receive messages, they know exactly what they’re getting:

• What types of messages subscribers will receive (i.e., promotional and marketing messages, transactional messages, appointment reminders, etc.)

• Approximate message frequency

• Statement that message and data rates may apply

• Links to terms and privacy policy

• Clear instructions on how to opt out

Explicit consent must be obtained through affirmative action, such as a customer actively checking a box, texting a keyword, or submitting a form. Implied consent or pre-checked boxes aren’t sufficient in most jurisdictions.

Still have compliance questions? Check out our ultimate SMS compliance FAQ.

Every SMS marketing program must provide a simple opt-out text message mechanism. Common methods include:

• Replying "STOP" to any message

• Clicking an unsubscribe link

• Texting a dedicated opt-out keyword

When a customer opts out, your system must:

• Immediately cease sending further messages

• Send a one-time confirmation of their opt-out

• Maintain records of the opt-out for compliance purposes

Sending marketing messages to customers after they have opted out of SMS can be legally risky for brands. Hence, tracking consent and compliance is crucial for all businesses. 

Maintain comprehensive records of:

• When and how each customer opted in (digital or physical form, online form, paper form, verbal opt-in, etc.)

• The exact disclosure language shown at the time of opt-in

• Date and time of opt-in

• Any subsequent opt-outs

These records are your first line of defense in case of compliance questions and should be maintained for at least four years.

Postscript is driving the charge in SMS campaigns, including boosting your opt-ins. 

Here’s how we do it.

Postscript’s SMS marketing platform integrates directly with your Shopify store, making the implementation of opt-in forms and processes straightforward. 

This integration ensures customer data flows smoothly between your e-commerce platform and your SMS marketing campaigns.

Postscript provides highly customizable on-site opt-in tools that allow you to:

• Create branded pop-ups and embedded forms

• Deploy targeted opt-in offers based on customer behavior

• A/B test different opt-in approaches

• Implement both single and double opt-in workflows

Compliance is built into Postscript’s DNA. The platform automatically:

• Includes required disclosures in opt-in forms

• Processes opt-out requests instantly

• Maintains comprehensive records of consent

• Updates as regulations change

This built-in compliance framework lets merchants focus on growth rather than regulatory concerns.

Once customers opt in, Postscript’s advanced segmentation allows you to create targeted SMS campaigns based on:

• Purchase history

• Browse behavior

• Engagement levels

• Customer attributes

This segmentation capability ensures the right message reaches the right SMS subscriber at the right time, maximizing engagement and ROI.

Postscript provides detailed analytics on:

• Opt-in conversion rates

• List growth velocity

• Subscriber engagement

• Revenue per subscriber

These insights enable you to continuously optimize your SMS opt-in strategy and marketing performance. 

Effective SMS opt-ins are the foundation of a successful SMS marketing program. By implementing the strategies outlined above and leveraging Postscript’s innovative tools, like CashBack, you can build a compliant and engaged subscriber list that drives significant revenue.

The future of e-commerce belongs to brands that can create personalized, direct relationships with customers. SMS messages provide the perfect channel for this connection by being intimate, immediate, and incredibly effective when done right.

Ready to transform your SMS list growth and make text message marketing your highest ROI channel?

Explore Postscript today and discover why Shopify merchants see an average of 15% more revenue after switching to our platform. For additional SMS marketing inspiration, check out our collection of fantastic texts from top-performing brands.

Want to level up your SMS strategy even further? Download our 2025 SMS Marketing Calendar for year-round campaign ideas and timing recommendations.